>> sreenivasan: all that and more, on tonight's pbs newshour. >> major funding for the pbs newshour has been provided by: >> ♪ love me tender ♪ love me true we can like many, but we can love only a precious few. because it is for those precious few that you have to be willing to do so very much. but you don't have to do it alone. lincoln financial helps you provide for and protect your financial future, because this is what you do for people you love. lincoln financial-- you're in charge. >> fathom travel-- carnival corporation's small ship line. offering seven-day cruises to three cities in cuba. exploring the culture, cuisine and historic sites through its people. more at fathom.org. >> bnsf railway. >> genentech. >> supported by the john d. and catherine t. macarthur foundation. committed to building a more just, verdant and peaceful world. more information at macfound.org >> and with the ongoing support of these institutions: >> this program was made possible by the corporation for public broadcasting. and by contributions to your pbs station from viewers like you. thank you. >> sreenivasan: the debate over hillary clinton's e-mail practices, as secretary of state, is back on the boil. it moved there today with a leaked report from the department's inspector general. the report found that clinton ignored clear directives about using a private e-mail server. and, she never received approval to use it for government business. it says previous secretaries were lax about e-mail security as well, but the rules were tougher when clinton took office. >> the policies, the regulations regarding the use of private email have only really been clarified in the past several years. up until that point, again, understanding that it was not encouraged to use personal email, but it was not prohibited. >> sreenivasan: clinton has acknowledged that, in retrospect, it was a mistake to use a private e-mail server. we'll get deeper into the inspector general's report, after the news summary. >> woodruff: in the day's other news, eleven states have filed suit over a federal directive on public school restrooms. the obama administration has said states must let transgender students use bathrooms according to their gender identity or risk funding cuts. texas and ten other states argue, the directive amounts to "a massive social experiment" that flouts the democratic process. >> sreenivasan: the man in charge of airport security nationwide pledged today to do something about lines that are getting longer and longer. peter neffenger is head of the transportation security administration. he told a house hearing that the t.s.a. expects to add nearly 800 more screeners by mid-june, but he warned that still won't be enough. >> i do think that we are at a lower staffing level than we need to be to meet peak demands at peak periods, and we're working the staffing models now aggressively with the airlines to determine the right number. >> sreenivasan: this week, neffenger ousted the official in charge of day-to-day security operations at the t.s.a. >> woodruff: in afghanistan, taliban leaders announced they've chosen their top islamic scholar as leader. mullah haibatullah akhundzada is expected to continue a hard line against peace talks. he had been a deputy to mullah akhtar mansour, who was killed in a u.s. drone strike last week. today's announcement came as a taliban suicide bomber struck in the afghan capital, kabul. the blast killed at least 11 afghan court emoyees on a minibus. >> sreenivasan: the government of israel tilted further right today as prime minister benjamin netanyahu named a fiery ultra- nationalist to be defense minister. avigdor lieberman is one of israel's most polarizing figures. at a ceremony today, lieberman tried to strike a softer tone, while netanyahu insisted he is still committed to a peace process. >> woodruff: and now to a growing fuel crisis in france. union workers are targeting the nation's fuel depots to protest a bill that would make the work week longer and layoffs easier. neil connery of independent television news reports from calais. >> reporter: in paris and across many parts of france, the fuel blockades are having a growing impact on drivers. frustrations are boiling over as petrol and diesel stocks run low. the french government insists there's no need to panic buy, but many motorists aren't taking any chances. >> ( translated ): from last night until 1:00 in the morning, i searched for petrol. this morning both of our two cars were on the minimum level of petrol. we needed to drive our children to school and to go to work. >> reporter: the trade union blockades over proposed labor law changes have become a test of wills with the french government. oil refineries are being targeted and the disruption is being felt far and wide. the government has been forced to delve into emergency petrol reserves for the past two days. this was the scene in normandy as one main route to the ferry port of le havre was blocked by protesting workers. >> reporter: ships blocked at sea as protest spread. >> sreenivasan: and to asia, where president obama wrapped up his visit to vietnam today and headed to japan. he concluded with a town hall meeting in ho chi minh city, urging young people to tackle climate change, and press for greater freedoms. later, crowds lined the streets as he left for the airport, and a flight to shima. there, he appeared with prime minister shinzo abe, and reflected on his planned visit to hiroshima. >> war involves suffering. and we should always do what we can to prevent it, but i am the president of a nation that at times is threatened by very real risks, not imaginary risks, and it's important for us to act on occasion to ensure that the american people are protected. >> sreenivasan: no u.s. president has ever visited hiroshima, where the u.s. dropped the first atomic bomb, in 1945. prime minister abe said today he has no plans to visit pearl harbor in hawaii, where japan launched a surprise attack in 1941. >> woodruff: back in this country, there's word federal agencies are wasting billions on maintaining computer systems that date back 50 years in some cases. the government accountability office reports it's eating up three-fourths of the federal technology budget. examples include a network for nuclear forces that still uses floppy disks, and agencies that rely on a microsoft windows version from 1992. >> sreenivasan: and, wall street rallied again, on hopes the global economy might be stabilizing. the dow jones industrial average gained 145 points to close at 17,851. the nasdaq rose more than 33 points, and the s&p 500 added 14. still to come on the newshour: why hillary clinton's email issues are being deemed more serious than her predecessors'; backlash against the v.a. secretary for comparing hospital wait times to disneyland; what we know about radiation-- 70 years after hiroshima, and much more. >> woodruff: we take a closer look now at the state department's inspector general report on hillary clinton's use of a private email server. rosalins helderman of the "washington post" joins us to help dissect the details. welcome back to the program, rosalind helderman. so, first tell us what would you say the main findings of this report are? >> so this was a report that looked at e-mail use by the past five secretaries of state, and it concludes that there have been systemic problems in how the state department has gone about preserving public records over the course of the tenures of multiple secretaries of state state. however, it was particularly critical of hillary clinton and her use of private e-mail. it said, for instance, that, that use did, in fact, violate department policies that were put in place to ensure compliance with the federal records act, public records laws. >> woodruff: and does it say that the rules, the guidelines were clear, should have been clear to secretary clinton and the people around her? >> one of the big takeaways of the report was that the guidelines had been not as clear as they should be going back over a number of years, and that in fact the guidelines and training on those guidelines have not kept up with the way that e-mail has changed the way that we communicate. that said, the report does specifically say that the warnings about the risks of using private e-mail for public business and the discouragement from doing so have become much more numerous and pointed and descriptive while secretary clinton was in office. and so, whereas her predecessor, secretary pollin powell was also criticized by the report for using private e-mail, the dangers of doing so might, perhaps, have been more clear to secretary clinton. >> woodruff: i guess what i'm-- what i'm trying to get at is, is there any doubt that the people around secretary clinton-- and i guess there's no way to know what she knew-- but is there any doubt that the people around her knew that they were in violation of a set of guidelines? >> they've said that they did not know that they were in violation, and one interesting thing is she and her aides have said that she wants to cooperate with all these inquiries, but, in fact, she did not sit with an interview forw the state department's inspector general and a number of the top aides did not respond to the-- while they were doing this. >> woodruff: is it known why they didn't cooperate? i guess the report says she's the only one of the former secretaries of state who did not. >> that's right. the other four or fev, including current secretary john kerry, did sit for interviews. the report does not-- does not provide a reason why she did not. >> woodruff: rosalind helderman, how does this contrast with what hillary clinton herself has said about this whole business? >> well, in some ways, it fits with what she has said. although, it takes a much more critical view of those things. for instance, she has acknowledged that she didn't seek approval. the report criticizes her for doing that, saying that she should have sought legal review and had other people weigh in on the security of the system. >> woodruff: one other, i think, question on everybody's mind is what about the security breaches? does the report get into what security was put at risk or security-- what information was put at risk because of the fact she used this private server? >> the main point of the report was to look at recordkeeping, and the federal records law. so it specifically says that it was not intended to look at the security of the system. however, it does say two interesting things about security, one is that it just notes that she did not provide a full briefing to cyber-security officials within the department about what kind of encryption and other safeguards were in place on the system and it's critical of that. and then the other is that it notes that there were several times where people expressed fears that the system might have been hacked, not necessarily that it was hacked, and her people have said that it was not. but they expressed fear that it meeive hacked and those potential breaches were not reported to cyber-security officials, which is another violation of department policy. >> woodruff: can rosalind helderman, just quickly, am i right that the report says hillary clinton, the people around her, took her e-mails with them when she left office, did not provide a copy of them until a delayed period of time? >> yes, that's right. it's quite critical of that, noting that she could have, even though she was using private e-mail, which is discouraged, she could have ensured that the record was kept by either printing e-mails at the time of her sending them and saving them-- obviously, having staff do that-- or leaving behind all of her work-related e-mails when she left the department in february 2013. instead, that process of not completed until almost two years later, december 2014, after the state department specifically requested them. >> woodruff: and finally, ros, any connection between this report and what we know is an ongoing f.b.i. investigation? >> there is not a connection. in some ways, they're looking at two different things. this report looked at recordkeeping and the federal records act. the f.b.i. investigation, from what we know, is looking at whether classified material was mishandled, sort of the security of the system. that is ongoing. the f.b.i. director has said that he feels no external pressure to wrap that up, although he does know that people are anxious for its results. >> woodruff: roz helderman with the "washington post," we thank you. >> thank you. >> woodruff: beyond the details of the report, there is, of course, the politics of clinton's emails. and while the issue has followed her throughout the campaign on the republican side, new protests-- some violent-- have swarmed around the g.o.p.'s presumptive nominee. john yang reports on the latest twists and turns on the campaign trail. >> reporter: at a rally in anaheim, california, donald trump pounced on the state department report on hillary clinton's e-mail practices: >> as i say, "crooked hillary"-- "crooked hillary." she's as crooked as they come. she had a little bad news today, as you know. some reports came down that weren't so good. not so good! the inspector general's report-- not good! but i want to run against hillary. >> reporter: a clinton spokesman claimed the audit shows her e-mail use was consistent with past state department practices at state. the candidate kept her fire trained on trump, and remarks he made in 2007, at the beginning of the housing meltdown. >> donald trump rooted for the housing crash that cost five million families their homes. i'm not making this up. we called him out yesterday using his own words. and his response? well, he bragged about what he did. he said, "that's the kind of thinking our country needs." >> reporter: massachusetts senator elizabeth warren-- neutral in the battle between clinton and bernie sanders-- picked up the theme as she emerges as one of trump's fiercest critics. >> but donald trump was drooling over the idea of a housing meltdown because it meant he could buy up a bunch more property on the cheap. what kind of a man does that? a small, insecure money-grubber who doesn't care who gets hurt so long as he makes a profit off it. >> reporter: at his own event last night in albuquerque, new mexico, trump laced into clinton: >> and i see this low life she puts on an ad, "did you know that donald trump was rooting against housing, because he wanted housing to go down, because he wanted to buy," and they've got some clip of me from many years ago where i'm saying "yeah, if it goes down i'm going to buy." i'm a businessman, that's what i'm supposed to do. that's what i'm supposed to do. >> reporter: but his rally's message was overshadowed by violent protests outside. demonstrators threw burning trump t-shirts, rocks and other objects at officers. police said they responded with pepper spray and smoke bombs. they said several officers were hurt, and at least one person was arrested. inside the hall, trump faced near constant interruptions. >> you can get him out. get him out, get him out. >> reporter: newshour special correspondent kathleen mccleery was there. >> that was a woman who was literally dragged down the stairs. there was a man who ripped his shirt off and they dragged him away. and of course one that got everybody's attention was a young boy, he didn't look like he was more than 10 or 12 years old, and he stood up and said something. i couldn't hear what he had to say, but of course i heard what donald trump said, and what he said was, that's the youngest protester he's had at any of his rallies and the kid must still be in diapers. >> how old is this kid? how old is this? get out of here. still wearing diapers. >> reporter: police and protesters were out in force at trump's event in anaheim today. the candidate also came under new scrutiny on a different front. in january, he skipped a republican debate and held an event to raise money for veterans' groups. >> i didn't know we would raise $5 million -- we actually raised closed to $6 million to be totally honest. donald trump gave $1 million dollars, okay? >> reporter: as it turns out, trump never actually made good on that donation-- until now. "the washington post" reports that earlier this week, the new york billionaire took steps to send $1 million to a foundation that aids families of fallen marines and federal law enforcement officers. in the meantime, trump added more delegates in tuesday's washington state primary. he's now just 41 short of clinching the g.o.p. nomination. for the pbs newshour, i'm john yang. >> woodruff: with more on this whirlwind day in politics, we turn to susan page, washington bureau chief for "usa today;" and reid wilson, chief political correspondent of the morning consult. and welcome back to both of you. so let's start, susan, with this state department inspector general report on hillary clinton's use of a private e-mail server. how much political damage is this likely to do? >> you know, it don't think it's hugely explosive. people who like hillary clinton will still like her, but i don't think it's helpful, and it lays the groundwork for the bigger report to come, the f.b.i. report, that investigation into her exclusive use of an e-mail server is still going on. >> woodruff: how do you see this? >> there are two sides of the same coin. on the one hand it's a lot better for the clinton campaign that this came out in may rather than october. on the other hand, though, it reinforces one of the fundamental problems hillary clinton faces and has faced in most of her political career which is people don't believe she is honest and trustworthy. people don't believe she plays by the same rules. and that is a real problem when it come comes to swing voters--e the clintons throwing straight? they've just handed republicans and donald trump all the ammunition they want to make that charge expoafer over. >> woodruff: and it looks like the republicans are going to keep talking about it. >> guaranteed that they will, because this is an issue that goes to that fundamental issue of honesty and trustworthiness. it will be something we will hear about over and over again over the next six months. >> woodruff: let's talk about donald trump. reid, as we were just reporting, this really he had last night in albuquerque, there were some protesters on the inside, but protesters on the outside were setting shirt on fire and throwing them, throwing bottles. we've now seen this at several trump rallies. is this the kind of thing that could hurt him or do people just say, "oh, that is tha just comes with the territory?" >> ting could certainly hurt him. it's sort of ironic that clinton is giving trump and the republicans all the ammunition they need and trump is giving clinton and the democrats all the ammunition they need. we've heard hillary clinton call trump dangerous, unfit for office. that's what these scenes of mayhem and violence look like. we heard from trump's campaign manager a few-- well, campaign chairman a few weeks ago, that he was going to act more presidential. i assumed that meant fewer of these big, boisterous, raucous rallies where he's kick protesters out. apparently, that's not the case. >> woodruff: i have heard some people say, susan, that this plays into the tough guy that trump presents himself as and really doesn't-- his followers don't mind it. >> i don't think his core supporters are put off by this at all. in fact, i think there is some risk for democrats if you have protests that turn violent against trump, you know, you think about the antiwar rallies of the 1960s. those often rebounded against antiwar candidates, antiwar presidential candidates like hubert humphrey. americans have a low tolerance for protests that turn violent. slight risk for democrats here. >> woodruff: let's talk about the other aspect of what's going on, on the democratic side, and it involves donald trump, but, reid, it's a new voice among the democrats and that's senator elizabeth warren of massachusetts. she's been tweeting a lot about trump, but yesterday, she was out making a public speech, and she was really tough on him. could she become, you know, a-- sort of an attack dog for hillary clinton? >> elizabeth warren is a hugely important voice within the democratic party. there is probably one other person who speaks for liberals as loudly as elizabeth warren and that's bernie sanders. so if and when warren is to come over to hillary clinton's side, her endorsement will mean a great deal in terms of healing the party. i think this is sort of the beginning steps of getting towards an endorsement of hillary clinton, the extremely likely eventual nominee, going after donald trump, sets up a contrast, no matter what a liberal voter thinks about hillary clinton versus bernie sanders, hillary clinton's a lot better for that voter than donald trump would be. >> woodruff: how do you see the role she plays. >> she's a great-- this is an example of how donald trump can do what hillary clinton hasn't done so far, which is unite the democratic party. elizabeth warren has not yet endorsed hillary clinton. >> woodruff: that's right. >> the two of them aren't really close. she's the only woman senator who has not endorsed hillary clinton yet. we assume she will eventually. this is an example of how she can be a really effective advocate for hillary clinton without even mentioning hillary clinton's name. elizabeth warren has figured out how to get under donald trump's skin. you can tell from his responses that he is disturbed by some of the criticisms she has made. >> woodruff: he came back and called her pocahantus, reverse to her talking about her tiny native american heritage, reid. trump isn't one to let any criticism lie, is he? >> although, susan brings up an important point here. there are a few things-- sure, he'll fire back at anybody over anything-- but there are few things that really bug him. elizabeth warren's criticism is one. questions about trump university have been another. questions about his net worth, especially, tend to get under his skin. republicans never figured out how to effectively go after trump and undercut him with his core supporters. you know, democrats only get one shot. they don't get a whole bunch of primarys. they only get the one shot in november. so they need to sort of start experimenting, figuring out the right way to undercut his support among, as many of his core voters as they can, raise his unfavorable ratings, make him unpalatable to swing voarktz and finally to get under his skin and make him look unpresidential. >> woodruff: let's talk, susan, about the contest out there, bernie sanders still very much competing, the two of them spending a lot of time in california. they're going to be voting june 7. what does california look like? >> we think hillary clinton has a lead there, significant lead, not an overwhelming one. it's her kind of state in that it's a racially very diverse state. that's been good for her. we think she'll win in california. she's almost guaranteed to go over the top, numerically clinch her nomination with the june 7 primary. the fact is, even if she loses in california, she's clinch her nomination in the california primary given proportional allocation of delegates. but i think it looks like she's going to win. and that will be important kind of psychologically to not have that last, biggest primary be one in which bernie sanders comes on strong and defeats her. >> woodruff: the optics could be gad for her if she were to lose. it's your sense that it's looking pretty good for her? >> that's what the public polling has shown. bernie sanders sort of needs an off ramp. he needs a reason to get out of this race. and losing california is that off ramp. it's going to be really tough for bernie sanders to say, "all right, i'm qight, "after he just won a bunch of state. there are four other states up, at least one of them, montana, south dacoat athose are probably states that will be better for sanders than they will be for clinton. >> woodruff: watching it all, reid wilson, susan page, thank you. >> sreenivasan: the department of veteran affairs is back in the crosshairs with its secretary, robert mcdonald, making some controversial comments. we had planned to interview the secretary today but his office called last night to say his schedule was now full. we hope to have an interview with him in the future. but we take a look now at the recent controversy and the persistent problems of delivering vets proper care. last night, the head of the v.a. posted the closest thing to an apology: "if my comments monday led any veterans to believe that i, or the dedicated workforce i am privileged to lead, don't take that noble mission seriously, i deeply regret that. nothing could be further from the truth." the comments that secretary bob mcdonald is referring to came monday morning at a breakfast with reporters, where he downplayed the importance of measuring wait times for medical appointments. >> what really counts is how does the veteran feel about their encounter with the v.a.? when you go to disney, do they measure the number of hours you wait in line? what's important? what's important is what is your satisfaction with the experience. >> sreenivasan: reaction was swift. a visibly-angry speaker of the house, paul ryan: >> when the v.a.'s secretary compared the lines at his agency to lines at an amusement park, we were dumbfounded. this is not make-believe; this is not disneyland, or wonderland, for that matter. veterans have died waiting in line for their care. clearly, the secretary's comments were not worthy of the veterans that he serves. but they're also indicative of a culture of indifference at the v.a. >> sreenivasan: republican conference chairwoman cathy mcmorris rodgers: >> when you go to disneyland, you aren't wondering if you are going to live long enough to make it to space mountain. clearly, the v.a. is not the "happiest place on earth," and veterans have died waiting in these lines. 18% of appointment cancellations go unfilled. we can do better. >> sreenivasan: however, veterans groups who have been vocal about problems at the v.a. offered a more nuanced reaction. >> his statements were certainly poorly wondered. i don't think they were-- they were meant to do any harm to veterans, certainly. i think that he's got a big job to do, and we need him to stick in that job and keep moving forward with his department to serve veterans better. >> thomas porter served in afghanistan and the persian gulf and is the legislative director for iraq and afghanistan veterans of america. >> sreenivasan: thomas porter served in afghanistan and the persian gulf and is the >> he's certainly changed the way the v.a. is look at the problem. he's been very transparent. he's been open with the v.s.o.s-- the veterans service organizations-- and he's making a genuine effort to address the problem. we understand the wait lines have been reduced dramatically since this scandal first started coming to light. we want to keep the v.a. going in that direction. >> sreenivasan: wait times for vets to see a doctor is a sensitive, and explosive, issue. the delays and a cover up cost the last v.a. secretary, retired army general eric shinseki, the job in 2014. after a v.a. doctor blew the whistle at a phoenix facility, an inspector general investigation found that phoenix-area veterans seeking care had to wait an average of 115 days, almost four months, for a first appointment. 1,700 veterans were kept off any official waiting list, and were at risk of being lost or forgotten. other investigations found this type of problem existed at many v.a. hospitals throughout the u.s. more recently the g.a.o. reported that the v.a.'s system for tracking how long veterans have to wait for an appointment was flawed, making it hard to identify and remedy scheduling problems. the v.a.'s network of hospitals and clinics is one of the largest health care systems in the u.s., with hundreds of thousands of veterans in need of care. >> woodruff: stay with us. coming up on the newshour: should the u.s. soldiers involved in the afghan hospital attack be court-martialed? but first, what science is still learning from the survivors of the hiroshima and nagasaki bombings. this week, president obama becomes the first sitting president to visit hiroshima. miles o'brien looks at how much of what we know about the impact of radiation comes from a study about the long-term effects there. it's part of our weekly series on the "leading edge" of science." >> reporter: the scientists who designed the first atomic weapons did not spend much time researching the long-term health consequences of their devastating creation. >> the manhattan project focused so much on physics, and really didn't know very much about the biological effects and health effects in particular. >> reporter: when i met him in 2012, radiation biophysicist evan douple was the associate chief of research at the radiation effects research foundation. the joint japanese and u.s. study has been following the survivors of the atomic bombings of hiroshima and nagasaki, for nearly 70 years. >> there isn't anything comparable to this kind of study. >> reporter: the work began almost immediately after the war, when president truman ordered the creation the atomic bomb casualty commission in 1946. >> the scientists have recreated through interviews and questionnaires the location of where each individual survivor was exposed, and so they could reconstruct by line of sight what the radiation quantities would be at different distances. >> reporter: 94,000 irradiated bomb survivors volunteered to become subjects. another 26,000 who lived in other japanese cities during the bombings but were not exposed to radiation, were included as a comparison-- or control group. today, about a third of the exposed and comparison subjects are still alive, many making routine pilgrimages up a hill overlooking the once devastated city of hiroshima to undergo medical exams. their blood is routinely analyzed-- researchers on the lookout for damaged chromosomes and other signs of disease. over the years they have frozen thousands of blood and tissue samples. >> if that survivor comes down with a cancer or a health effect today, one can go back into the freezer and perhaps find what changed in that individual that eventually ended up resulting in a cancer. >> reporter: researchers here have published hundreds of papers documenting the links between radiation and its ill health effects, primarily cancer. they've written the book that is the basis for the standards for acceptable radiation exposure. among the findings over the years: thyroid cancer and leukemia are the first to strike; solid cancers come 10-30 years later. young people are more susceptible to developing cancer than adults and women are more susceptible than men. perhaps most important: a single exposure increases cancer risk for life. the bottom line? of 94,000 survivors studied over 70 years, about 1,000 additional cases of cancer can be attributed to radiation from the bombs. >> so, the atomic bomb survivors study, which is a remarkable study, the gold standard in terms of radiation epidemiology. it has limitations, and one of the limitations is the dose was given all at once. >> reporter: radiation epidemiologist john boice is hoping to address that limitation. he is spearheading a study of workers from the manhattan project, atomic veterans who witnessed atmospheric bomb tests, utility employees at nuclear power plants and medical professionals, one million in all. radiation exposure data captured by the dosimeters routinely worn by these workers over the years is compared with their health history and cause of death. >> so, when we complete the study then we will be able to say what the risks are from these various levels of radiation. are they the same as hiroshima and nagasaki? are they lower? are they higher? >> reporter: some studies suggest our bodies can fight back and repair damage caused by low-level, yet chronic, exposure to radiation. but no one is sure. biophysicist david brenner is also hoping to fill in some of this uncharted territory. he is director of the center for radiological research at columbia university medical center. >> any level of radiation can produce d.n.a. damage which ultimately can produce a cancer. >> reporter: but when the doses get very low, scientists are hard pressed to quantify the link between radiation and cancer. there is just too much cancer out there already. four in ten americans will eventually battle the disease anyway. >> so how do you detect a very small increase and not 40%? if there was an increase some 40% to 40.1%, how would we ever detect that? that's really our problem. >> reporter: so could there be a line, below which there is no risk? >> what we're trying to do is to figure out what is the best way to extrapolate the risks that we know from high doses to low doses. in order to do that, we really want to know the mechanism on how exactly does radiation produce cancer. >> reporter: brenner employs a particle accelerator to try and find some answers. in experiments, he aims high energy protons at a single cell. >> what we want to do is to be able to expose a cell to radiation but not exposing all the neighbor cells to radiation because that's actually what the real life situation at very, very low doses. >> reporter: this isn't just an academic pursuit. the atomic bomb survivors study is the basis of risk estimates for everything from doses in medical care, to work rules for radiation workers, to evacuation orders in the wake of a nuclear power plant meltdown. but these rules, which can affect so many lives in so many devastating ways, are based solely on educated guesswork. in january 2015, the u.s. house passed the low-dose radiation bill which would provide funds to begin a large study. but the bill stalled in the senate, frustrating scientists who believe the nation that unleashed the nuclear age is obligated to never stop trying to fully comprehend its long- term impact. i'm miles o'brien, for the pbs newshour, in hiroshima japan. >> sreenivasan: in october 2015 an american ac-130 gunship pummeled the doctors without borders hospital in kunduz, afhganistan, hitting what the crew believed to be a taliban fighting position. the plane rained artillery and other fire on the facility, killing 42 people, despite frantic calls from the group, known by its french acronym "m.s.f.", to stop the attack. last month, an army investigation found there was no intent by the americans to destroy the hospital-- either by the air crew or the american special forces on the ground who were calling in fire. the probe found that it was a targeting error borne of confusion and miscommunication in the fog of war. 16 soldiers were reprimanded but no criminal charges were filed. but a new report in the "new york times" magazine by matthieu aikins of the "nation institute" casts doubt on the motivations of the afghan troops who told the americans that the hospital was a taliban stronghold. i spoke with aikins yesterday, and with two former military attorneys; i began by asking the reporter what may have motivated this attack. >> from the extensive reporting we did starting from november, as well as documents that are buried in the military's docket report, there's evidence that afghan fors may have provided an exact description that masmed the hospital as a target, meaning that they intentionally targeted the hospital, leading to u.s. forces perhaps unintentionally striking the hospital as a result of that description. >> sreenivasan: so why would afghan forces want to strike a hospital? >> there's been a long-simmering tension between m.s.f. and the afghan government, basquely a collision between two different world views. m.s.f., which sees itself as a neutral humanitarian medical organization that treats all sides to a conflict, regardless of who they are, and afghan forces that have resented m.s.f. treating what it views as the enemy. >> sreenivasan: so is there a widespread mistrust? >> what we found, you know, when you went to kunduz was a resentment and mistrust of m.s.f. on the part of the afghan forces. they told me they thought that m.s.f. was supporting the taliban, and this, you know, later led to what turned out to be false beliefs that m.s.f. actually had been taken over and there were taliban leadership inside the hospital at the time it was struck. >> sreenivasan: you've read the official military account. you've done your own reporting. are there discrepancies? >> i think that what's unexplained in the military's report, is that the arc de triomphe the gunship that struck hospital after its navigation system failed, it then relied on a visual description of the target that was given by the special forces ground commander. and that description, as the military admetz, came from the afghan forces. the military basically asked the afghan forces what they wanted to hit. and while the coordinates for the other target, you know, the intelligence headquarters were passed on, those were correct coordinates, they were passed on much earlier in the evening, around 6:00 p.m., according to the military. around 1 a.m., an hour before the strike when the military goes back and there is confusion because of the failure of the navigation system and asked the afghan forces, "what should we be hitting here?" the afghan forced gave a description that resembled the hospital and in no way rezems the intelligence headquarters. >> sreenivasan: they described it asab uncontrolled operation in a crowded area. is there evidence of that? >> yeah, i think this is a very crowded city. it's afghan's fifth largest city, and the fact that they're blindly striking eventually a target in a crowded area raises questions of recklessness andings in. but we actually go further than that saying the afghan forces may have intended to deliberately target the hospital. >> sreenivasan: you also sight different correspondents, members of the headlight involved in the operation had with members of congress other ands. what was your view of what was happening at the time and did that change after the fact? >> well, absolute. we were provided with an e-mail from one of the special forces troopers on the ground who said that, you know, there were taliban inside. they had kidnapped the doctors and they had taken it over. basically, suggesting that the american forces on the ground had come to believe the false reports that, you know, afghan forces told me they believed, that they provided to american forces, that the hospital had been taken over by the taliban, which is very trouble, and, again, it's something not really contained within the military's report or addressed by their investigation. >> sreenivasan: one of the members of the m.s.f. told you at the end of your story about the possibility of ever working in a place where so many u.n. security council members are involved in confer conflicts. >>un, this has been a trend around the world. hustrikes against m.s.f. facilities in syria, in yemen, in sudan, and in other areas. the fact that m.s.f. is being targeted is extremely worrying development and one that, you know, has been taken to the security council. >> sreenivasan: matthieu aikins joining us from athens. thanks so much. >> my pleasure. >> sreenivasan: we take a deeper look at the u.s. military's investigation of the attack on the doctors without borders hospital in kunduz and whether the probe should have gone further with retired marine corps lieutenant encourage gary solace, who served as a judge advocate and military judge during his 26-year career and teaches the law of armed conflict at georgetown university. and retired lieutenant colonel jeffrey adocat, who servedda as a senior legal advisers to special forces. he is the director for law at st. mary's university of law in san antonio. the military admits a series of cascading errors that led to this tragedy. what was the most egregious to you? >> to me the most egregious was the pilot was unsure of his target was unsure of the target for an hour as he circled overhead and fired, despite apparently not being all that sure of his target, even two minutes after he initiated the first volley, he radioed jtac on the ground, asking for confirmation that he had hit the target. he still was unsure he had hit the correct target, and to me that's the most egregious of a series of errors that were made. >> it's 2:00 in the morning. the fog of war, again, the report report found no intentional misconduct on the part part of the american forces. it's a tragedy, it's a horrible tragedy, and it shouldn't have happened but it did happen. our toolbox is not the anglo-saxon law, it's the law of war when we judge these things. >> sreenivasan: there seems to be a distinction between intent andings in. just because you do not intend to do something does that let you off the hook of negligence? >> it doesn't let you off the hook, but we're talking about whether there's a grave breach of the law of war. i don't see a gray breach of the law of war primarily because mistakes were made, communication breakdown, and if it's true that we had faulty intelligence from the afghans, then the investigation should be reopened. but that still wouldn't, you know, alleviate the report here that we have indicating no intent on the part of the americans to target this particular facility. >> sreenivasan: gary solis, i saw you shaking your head a couple of times there, if you were prosecuting this, how would it? >> there is negligence and culpable negligence. if it's more than mere simple negligence, then you have a prosecutable case. to my mind, the fact that he fired anyway, despite fact he had lost his guidance system and his aircraft navigation system had previously gone down, his video antenna was gone, he was unsure of the target-- those things combined, to me, raise a colorable case of culpable negligence, which in my mind should have been decided by a military jury. >> sreenivasan: and jeffrey addicott, why not a military jury? why not a courts martial instead of the legal process that took place? >> i don't think it's necessary. we had three generals from outside the theater come in. we had interviews by 65 witnesses, 3,000 pages of investigation, lots of judge advocates, higher in rank than gary and myself, looked this thing over, mulled it over. and i think they came up with the right conclusion-- no intent and, therefore, you know they decide to handle it at a lower level which is in accordance with the law of war. i'm not going to second guess them. >> sreenivasan: gary solis, did the investigation do as best as it could. the moostles said they wanted an outside investigation. it doesn't make sense for the people who committed the crime to be investigating it? >> i don't argue that didn't do the-- the investigator didn't do the best that he could. i simply disagree with his conclusion, and that is that in this situation, given the circumstances of which the aircraft commander and his sensor operator aware, they went ahead and fired on a target of which they were not sure. >> sreenivasan: jeffrey addicott, why not have a jury take a look at this? >> the moment of absolute certainty in combat never arises. if we're going to wait and hold that standard to soldiers, we're just going to sit in the fox hole and never shoot because i'm not quite sure i have the right thing. the law of war doesn't require that. if it did, we might as well just pack our bags and leave now. >> sreenivasan: gary solis, what about unfortunately we can't have a judge authorize every bullet fired? >> i've been in combat and called in supporting fire from ac-130s, and you're never positive, but the law does not require that you be positive. and it does allow for negligence, in which case, if it was simple negligence, i would agree, but i simply believe that given the series of mechanical failures in the aircraft, and the indecision of the pilot even before-- even after he fired, indicate culpable negligence. >> i would agree if the building was marked, but the building was not marked. these people did not mark that facility, and we can't expect these people to do the monday morning quarterback, look over their shoulder, be hypersensitive about it. their obligation was to mark the building. there were no marks, no red crescent on there. we can't hold our soldiers to this supercelluous standard. >> sreenivasan: jeffrey addicott, the m.s.f. has said we gave you, the military, the g.p.s. coordinates. we gave it to you a couple of days before. what else could we possibly do and we were actually flying a flag? yes, it was 2:00 in the morning, and weert only one with the lights on in a city that has no power. what else could the m.s.f. have done to protect themselves in this case? >> have a reflective device that's on the roof that has the red cress onto it. they could do that. they didn't do it. >> sreenivasan: exwaer solis, what about the idea we heard from the reporter that there might be ape different motive behind it, that the afghan forces there had this kind of mistrust and might think this is a place where they are harboring taliban leadership and this should be air fair place for us to go after? >> i think the report by matthieu aikins, if it proves to be true, could provide evidence that shows that the indecision was mere negligence. in other words, it was excusable, given the circumstances. so far what we know is what he did and what he, the pilot, reported in the investigation, which, of course, i have not read. 3,000 pages long, i don't know if it's been released in full to the public. yes, i think that that report could provide evidence on behalf of the pilot and the sensor operator on the plane. >> sreenivasan: jeffrey addicott, what about that? >> real-time information on the ground, this is the target. obviously the person providing that false information needs to be prosecuted, but that overrides, then the pilot could say i have certain information from the ground and i'm assuming they're our allies and i'm assuming it's correct information, so i'm going to go ahead and target and fire. >> sreenivasan: all right, jeffrey addicott, gary solis, thank you, both. >> woodruff: finally, a newshour essay. biologist sheila patek has faced criticism for her research on mantis shrimp and trap-jaw ants. lawmakers have called her studies a waste of taxpayer money. tonight, she explains how dismissing her work misses the aim of scientific research and discovery. >> some years ago, i presented my lab's discoveries to a group of leading thinkers and public figures. we discovered that mantis shrimp use hammers equivalent to the mass of two toothpicks and move them with the acceleration of a bullet to pulverize thick snail shells. we discovered that tiny trap-jaw ants close their jaws with 100,000 times the acceleration of a sprinting cheetah. i expressed the wonder of these discoveries as well as their fundamental significance to our understanding of physics, evolution, and the limits of current engineering capabilities. a prominent lawyer from nigeria, who was in the audience that day, approached me a few days later. her first words to me were, "your research disgusted me with such waste-- studying trivial and useless problems." in that moment, she had voiced my most vulnerable thoughts: that the science to which i'd dedicated much of my life was actually pointless. "but," she added, "i realized something important, that science is about discovery, not just about solving human problems." she then spoke a phrase that has stuck with me over the years. she said: "i want what you have for my country." in her country, nigeria, there was simply no infrastructure for this type of discovery-based research. in fact, many solutions to human problems began in a scientist's laboratory through discovery- based research. did you know that some of the most significant medical breakthroughs for the human brain began with research on sea slugs? the value of my work came under attack again when republican senator jeff flake featured it in a wastebook. that's a partisan report that highlights what some in congress see as wasteful government spending. they ridiculed a research project in my lab that showed how mantis shrimp use their lethal weapons to resolve conflicts without killing each other. needless to say, this is a fundamental question for any animal or human system that has lethal capabilities. in response to the wastebook attack, i was invited to present my research on capitol hill to senator flake came to the event and i presented my research to him, individually. i told him the story of one of the many unanticipated paths from my lab's discoveries to human applications. i explained how the extraordinarily intense impacts of mantis shrimp hammers inspired engineers to make new materials that mimic the structure of mantis shrimp hammers. now these materials are moving toward use for lightweight, impact resistant sports helmets and military armor. he actually seemed engaged. so i asked him, did any of my research seem worthwhile? senator flake said yes. he was especially interested in the novel engineering products. these fundamental discoveries and their potential for translation are why my research program is funded by the department of defense, the national science foundation and other organizations. however, engineering-related applications are not the primary reason we do this research. the nature of discovery is that it is impossible to anticipate what you'll find. discovery-based research is most fruitful when new knowledge is sought for its own sake and this >> woodruff: on the newshour online right now, new clues to the earth's early atmosphere may be trapped in fossilized bubbles in ancient lava. and scientists say the findings could redefine our search for life beyond earth. read more on our science page. all that and more is on our web site, www.pbs.org/newshour. >> sreenivasan: tune in later tonight on "charlie rose:" british novelist julian barnes. and that's the newshour for tonight. on thursday, get a front row seat for a new music variety show, "live at 9:30." i'm hari sreenivasan. >> woodruff: and i'm judy woodruff. join us online, and again here tomorrow evening. for all of us at the pbs newshour, thank you and good night. >> major funding for the pbs newshour has been provided by: >> bnsf railway. >> lincoln financial-- committed to helping you take charge of your financial future. >> fathom travel, offering cruises to cuba and the dominican republic. travel deep. >> genentech. >> supporting social entrepreneurs and their solutions to the world's most pressing problems-- skollfoundation.org. >> supported by the rockefeller foundation. promoting the wellbeing of humanity around the world, by building resilience and inclusive economies. more at www.rockefellerfoundation.org. >> and with the ongoing support of these institutions and individuals. >> this program was made possible by the corporation for public broadcasting. and by contributions to your pbs station from viewers like you. thank you. captioning sponsored by newshour productions, llc captioned by media access group at wgbh access.wgbh.org this is "nightly business report" with tyler mathisen and sue herera. what's changed. the rally is building so why are the markets stressing about all the things that used to have them so worried? today we face a crisis in our airports. we've all red the headlines. three hour long security lines. tempers flare in congress and at airports but delta and the tsa may have found a solution to get you through security more quickly. science or science fiction, medical technology is advancing faster than ever before changing the way we treat illness. the first part of our modern medicine series begins tonig