just ask them, and they'll tell you. if you don't think fearless at 50 when you think aarp, you don't know aarp. see more real stories at aarp.org/fearless50. >> and now, bbc "world news america." katty: this is bbc "world news america." amorting from washington, i katty kay. so-called islamic state is gaining territory. we are in benghazi. the wild close i on markets. the federal reserve expresses concern about the u.s. economy and keeps interest rates unchanged. man and machine go head-to-head in the complex game of go. who came out on top. welcome to our viewers on public television and america and around the globe. the city of benghazi is known to many as the place with a libyan uprising started five years ago and where the u.s. consulate came under attack. today it is the site of a ferocious battle against the islamic state. the coalition is struggling to hold its ground against islamic militants. one of the few journalists able to get inside the city sent us this exclusive report. >> struggling to hold their positions. these fighters are working with the army trying to stop the advance. we are some of the few journalists to access these frontlines. it is impossible to reach this area with out the protection of these fighters. this was the city that started the revolution five years ago. look at it now. neighborhoods have been destroyed. thousands have fled. the armed forces still control most of the city. up here on the side of the road is the only influence. if you come with me you can see how the front line has moved .orward inside these damaged buildings are fighters and the entire areas under threat. a growing number of commanders and army leadership. the situation was a political dispute. there's a big disagreement between a front-line commanders, the leadership, and the politicians. just a few hundred meters away rom the frontline -- it has been hit before. children are desperate for an education. you can hear the gunfire constantly. their teacher tries to reassure them everything is fine. after missing almost two years of school, these children's futures are bleak. --rom the chaos of benghazi the so-called islamic state. visibleheir black flag from the only entrance into the city. growing asence is fighters from other islamic nations join them. on the frontline, the men rest after a long day. all of them say they will keep fighting. within the armed forces grows, so does their sense of identity. bbc news, benghazi. katty: a rare look inside benghazi. for more on the spread of the islamic state i spoke with chuck hagel, president obama's defense 2013 to february of last year. secretary hagel, we just heard about the expansion of the islamic state's reach in libya. extension oft the the reach in afghanistan. afghanistan to libya, how far will the movement spread? sec. hagel: it is already spread throughout the middle east and northern got. it is a combination, a strange combination, of ideology, a warped sense of what the islamic caliphate could be. and anger, a resentment that has been built up. it is a combination of those. it is a toxic brew that attracts millions of disconnected and disinfect did. -- disaffected. there are millions throughout the world. media has empowered that voice. it is not only about a confined part of the world. i think we will be dealing with this for a long time. katty: in august of 2014 when they were moving quickly through the middle east, you said this is something we have never seen the war here it you got pushed back on the white house for sounding alarm bells? sec. hagel: that is true. partly because the president described it differently. and, i can understand, the white house politically did not want to overstate the seriousness of the threat. there may be other reasons, but my job was the defense of the country. i have always believed, and always tried to do in every job i've ever had, to say things plainly and clearly. that has not always endeared me and has gotten me in trouble, not working to my political been a hit. we have to be careful not to overstate, but we have to be clear with the american people that it was a clear threat that we had never confronted before. katty: you said we cannot bomb our way out of this problem. are you convinced today, having been out of office for year now, that the u.s. has a plausible expected strategy to deal with the threat of islamic state? sec. hagel: i think we're getting there. this is difficult. it is complicated. it is deep, historic, as well as all of the other dynamics i mentioned. we're constantly adjusting. democracy,trength of our institution, they are imperfect -- as all institutions are -- but we can be agile to we are smart and forward inking -- forward thinking. fory: this is been going on four years. we have to be a bit quicker? sec. hagel: we underestimated the situation. have paralyzed our strategy in many ways in syria because we are captive to the assad must go. we cannot move without that being addressed first. i'm not sure that needs to be addressed first. the first thing that needs to be addressed is to build a platform of stability including the iranians, the russians, the states and the united to bring stability to that region so you can start, hopefully, resolving and solving what is going on. we have never seen anything like this in the middle east. you have countries with no government. it is getting deeper. katty: it is reflected on the campaign trail in the united states. you are a former republican senator. some of your colleagues on the campaign trail have talked about the threat of islamic states in terms of carpet bombing the middle east, taking the oil. what do you think of the republican candidates' solutions for what is happening with the islamic state? firstagel: let's take the solution offered by one of the republican candidate. -- republican candidates. that is insane. katty: the idea of carpet bombing? sec. hagel: if you follow that to the next steps, you would destroy the entire middle east. we are on our way to seeing that now, the destruction of the middle east, and structure, refugees, suffering, and killing. then you are locked in proxy wars with the russians, the withs, and others interests in the area. i give president obama credit -- he has not allowed the united states to get caught in down drafts of crises. that is difficult for president of the united states. everyone wants the united states in -- you need to be here, more boots on the ground, more military. i told the president when i was in the senate, once you commit you will not back out. you get deeper and deeper in. that is not the way to do this. the way to do this is to try to eace,a diplomatic p which i applaud john kerry for. there is a military role, sanctions, partnerships -- the things that have to come together to deal with this. there is no military solution to the problem. katty: secretary chuck hagel, thank you for coming in. president obama has called for urgent action to combat the zika virus, spread by mosquitoes and believed to be linked to brain damage in babies. the appeal comes after the world health organization warned that the zika virus is likely to spread through the americas. accessook had exclusive to a laboratory in texas where scientists are looking for a vaccine. is the latest virus do send shivers around the world. there is no vaccine for the zika virus. it has been spreading to 20 countries in the caribbean and latin america. lasten it reached brazil year it exploded in the americas and has spread quickly -- in fact in probably a couple of million people. james: should people be frightened? especially pregnant women? >> absolutely. if i had a daughter of childbearing age he was planning spring break in the caribbean, i would urge her not to go there. james: these young mothers in brazil didn't have that choice. the zika virus attacks the brains of unborn children, leading to severe disability or death. scientists from this high-security lab in texas have been gathering samples and brazil to find out more. so many questions, so little time. >> what animals does it infect? how long does it stay in humans? samples we have positive or negative? we have the beginning stages. this is the forefront of the work. james: the ultimate is to produce a vaccine. scientists could have one ready for testing next year. winning approval from regulators could take longer. developing an effective vaccine would take a short time, but it would take the longest time -- the process of putting it through the fda and other agencies to allow it for public use. that may take 10 years to 12 years. james: working with insects which can carry such a dangerous virus is not without risk. there are 15,000 mosquitoes in this room from a dozen different countries. there are cap under tight's -- they are kept under tight security conditions to make sure they cannot escape. people carry it from country to country, meaning the zika virus could spread anywhere the insects are present, including in the southern united states. james cook, bbc news, galveston, texas. katty: today, the u.s. federal reserve left interest rates unchanged and pledged to monitor developments in the global economy closely. the announcement came after the first hike in december. since then, financial markets have been driven lower by the slowdown in china and falling oil prices. i discussed it with mohamed el-elarian, the author of " the only game in town: central banks, instability, and avoiding the next collapse." were you surprised by that decision not to raise rates? i wasn't.an: they are having difficulty conveying a policy. it is unfortunate, but it is the reality. katty: the short-term reaction since the new year's, slowing demand from china and oil prices falling, markets going wild -- do you think this is a longer-term strategy the fed is waking up to, and it cannot raise interest rates as much as it hoped? dr. el-erian: there is a short-term issue, the global economy has become more challenged on account of market volatility and policy mistakes in china. that is true. the bigger issue is that we have over relied on central banks and on the fed. the fed is no longer able to deliver what it wants to deliver. that is getting exhausted and we have to make major decisions to avoid a worse outcome. katty: i was reading some of your diagnosis of the problem and the prescription. it seems you are saying the fed is trying to use a band-aid without addressing the wound. the band-aid is not big enough with the size of the injury. of long does this time last low growth and instability? dr. el-erian: it will come to an end. the fed was forced to step then, not because it wanted to, but because other policymakers were paralyzed by dysfunctional politics. the redhead and choice but to deal -- the fed had no choice but to do with a huge problem with inadequate tools. there is a limit to that strategy. they are seeing the stress, strain, and collateral damage of pursuing too many objects is with too few instruments. katty: we need the political instrument to work more effectively, there is no limit to political dysfunction -- especially not in the united states at the moment. dr. el-erian: i don't want to give up that easy. it is clear the citizens are asking for more. the reason we are getting the antiestablishment movements are a reaction to that. there is still hope the institution may respond. if it does and we will end of the world of recession and financial instability. katty: if you could say one thing to those running for the presidency of the united states that they need to do to ensure the health of the u.s. economy, what is it? dr. el-erian: structure growth, but her income distribution, dealing with debt overhang, and global cooperation. it is a political implementation issue. katty: the book is " the only game in town: central banks, instability, and avoiding the next collapse." thank you for joining us. you are watching bbc "world news america." still to count, donald trump announces he is skipping thursday's republican debate -- deciding to make his closing argument in iowa on a stage all his own. agents have surrounded a nature preserve in oregon urging protesters who sees the land on january second to leave. yesterday, several were arrested and one was killed. correspondent: the showdown came on a snowy stretch of highway in south central oregon. the police closed it off as the fbi moved in. five of those leading the protests were arrested with our cars were stopped, only after shots were fired -- leaving one injured and another dead. three other were arrested in separate locations. what is important to you? >> my family and kids. >> this is the man who died. he was interviewed by the bbc after the occupation began. he said he would rather die than be arrested. like several others, he traveled to oregon to join the sagebrush rebellion. they took over the headquarters of this wildlife refuge in a protest over grazing rights. the government owns half the land in oregon and limits local ranchers' ability to use it. protesters were asked earlier this month what it would take to make them leave. >> i wouldn't say words would do it. action word. or the federal government to remove its unconstitutional presence in the county. correspondent: he is one of those under arrest. the occupiers drove government vehicles at the refuge and seemed unstoppable. the authorities wary of provoking a bloodbath. some locals were frustrated by the standoff, but many say the ranchers' needs are more important than regulations. the arrests are a sign of new determination by the police to shut down the occupation. it is not over yet. bbc news. ♪ it looks like donald trump is still calling all of the shots in this presidential race, down to the british line. his latest move is refusing to republican debate tomorrow night over fox's choice of moderator in megyn kelly. the democratic race, senator bernie sanders, who is tied with secretary hillary clinton in iowa, met privately with president obama. i spoke with our north american reporter. donald trump has done it again. what does this do for him and fox news -- pulling out of the debate? >> in the past the discussion has been who makes the main stage and the kids table debate. donald trump is turning the whole thing into a kids table debate. katty: you think people want to in anymore? >> it will be a distraction. he will have his own rally with wounded veterans on the stage. some people will be watching one thing, others another. i don't know. katty: debates are part of the american political process. conventional wisdom has it that everyone wants to be in them because that is when you can persuade the voters. does donald trump think he doesn't need the debates anymore? >> he is ahead in the polls, and he may think there's more to again with a spectacle and sucking up the oxygen, having people talk about this, then being on the stage with the other candidates were everyone will take a shot at him because this is their last chance before the iowa caucuses? there is a risk you might be perceived as backing down from a night, or he is ruled by his anger -- they provoke him into doing something rash. every time, so far, he has ended up on top. katty: called to me about the democratic debate. bernie sanders, campaigning against hillary clinton, left the campaign trail in iowa to come to washington. why? >> it was a planned meeting, but the timing seems suspicious. katty: between the president and bernie sanders? >> exactly. president obama just had kind words for hillary clinton and brushed off bernie sanders. this could be an attempt to even the playing field. sanders coming-out of the white house, does that help with some of his supporters? >> helps with some and herds with others. bernie sanders' fan ofers are not a big barack obama. they feel disillusioned and are turning to bernie sanders, because they feel he would be able to advance a more liberal, robust agenda. katty: he is heading up to iowa tonight. i will see you up there. computere the modern was invented, there has been one question -- who is more clever, man or machine. the latest matchup has a computer beating a professional player at go -- the chinese game more complicated the entrance and played by what he million people around the world. our reporter has more. pointpondent: it is two 5000 years old, and the rules are simple. it is a game of complexity, and no computer has come close to humanng a champion. he played a computer program called alpha go and lost five times innovaro. it was developed by a british artificial intelligence company. player,tor, a go studied the patterns repeated in games. it plays different versions of itself millions of times. each time a gets slightly better. it learns from its mistakes. correspondent: they have taken on more and more complex games. in the 1950's it to be a game with thousands of possible positions. in the 1990's they cracked chess with 9 million possible positions after three moves. complexity on a different scale. here is how many different positions there are in one game. 10 to the power of 71. amongst those trying to build advanced artificial intelligence, readin -- beating go is being seen as a key moment. to solve thising problem. it has been seen as a landmark for artificial intelligence research. it is very impressive they have managed to get the people and resources to solve this. correspondent: there is a lot of human brainpower employed to win at go. now computers will move on to more complex tasks. bbc news. go.y: my that plays i think he will be sad to hear that news. that brings our program to a close. you can find out more on our website here he do can find me on twitter. i am @kattykaybbc. thank you for watching. do tune in tomorrow. ♪ >> make sense of international news at bbc.com/news. >> funding of this presentation is made possible by the freeman foundation, newman's own foundation, giving all profits from newman's own to charity and pursuing the common good, kohler foundation, pursuing solutions for america's neglected needs, and aarp. >> what is fearless at 50? just ask cynthia anderson, who jumped out of her own 50th birthday cake. boom. or how about dr. hector flores, who grabbed life by the microphone to do some improve. don't forget my man, guy ford, the firefighter who's lighting the business world on fire. just ask them, and they'll tell you. if you don't think fearless at 50 when you think aarp, you don't know aarp. see more real stories at aarp.org/fearless50. >> bbc "world news" was presented by kcet los angeles. captioning sponsored by newshour productions, llc >> ifill: good evening. i'm gwen ifill. >> woodruff: and i'm judy woodruff . >> ifill: on the newshour tonight: gunfire after a traffic stop. one militant is dead and eight others arrested while the f.b.i. surrounds a wildlife reserve where activist continue a three- week standoff. >> woodruff: also ahead this wednesday: on the ground takes from iowa and new hampshire, now just days from the first voting. >> ifill: and a new memorial to honor those who served in world war one. >> you can't understand the country we live in today, the world that we live in today, without understanding world war one, and this is our opportunity to try to do something with that. >> woodruff: all that and more on tonight's pbs newshour.