By another explosion inside the subway, not far away in brussels. And tonight, the search is on for one man believed to have survived, as Surveillance Video, a screen, one frame from Surveillance Video, shows three men walking together in the airport. They are carrying carriages of baggage, two of them are wearing only left gloves, believed to be masking detonation switches. This is the proportions here inside brussels. This is the airport not far away is the subway is to be, where it all happened. Theres the freeze frame of the two men. Note the left gloves, black gloves, on the two men wearing black. On the man on the righthand side of the frame in the beige jacket is believed to be with them, though separated by some distance, perhaps someone accompanying them to ensure they carried out their task. Both men on the left are believed to have died in the attack, detonated themselves. We begin another hour of coverage here tonight, and we want to welcome Michael Leiter on the air with us. He is the former director of the u. S. National counterterrorism center. He worked for president george w. Bush. He worked for president obama. And michael, i guess the question of the day is, how does the free world possibly win this . Well, brian, its an incredibly difficult fight. And what weve seen now in paris, then in San Bernardino, and now in brussels, is how resilient this enemy is. And what is, i think, most shocking about this attack is despite some really valiant and intensive efforts by the french, by the belgians, by their partners in the u. S. And the uk, that four months after paris, three days after the arrest of the lead planner, that this sophisticated attack could still occur. And that, i think, tells us many things, most of all, how difficult this enemy has become embedded into some of these centers in western europe. And isnt it true, michael, that the fight against terrorism is only as strong as the weakest link in the chain. So all the free nations on earth, we depende on all of the to launch a fight against terrorism within their borders. That is absolutely right. What counterterrorism professionals often say is, it takes a network to defeat a network. And the network youre trying to defeat here, isis, does rely we rely on a network of cooperative nations. Truthfully, europe is especially vulnerable. They are vulnerable because of their probatiximity to syria, a they are vulnerable because of much of what the European Union has developed over the past 20 years, opening up borders, relying on other states to protect the borders, farther from belgium or paris. They didnt, at the same time, integrate their intelligence and security services. So you dont have the network in belgium, in europe, in paris, the same way with truthfully we do in the United States. And that means there are numerous weak links in that chain. Having said that, youve always answered this next question honestly when weve posed it to you. How worried are you about the United States in light of this . Im worried, and i will say that counterterrorism officials here in the u. S. Are probably more worried than ive ever seen them. Not specifically about the u. S. , but again, about the scale of this threat globally and how they have seen it growing strategically, but the failure to intercept this attack tactically. I think on the u. S. Front, people should be concerned, because isis message does not respect borders. We, obviously, have the experience in San Bernardino. Weve had other attacks. So were borderless in that sense. But all that being said, the u. S. borders are more secure. We do share information amongst agencies more effectively than most places in the world. So, i think that there is certainly still risk here in the u. S. Were not going to detect and stop everything. But i think it would be far more difficult to have a network which begins, say, it had an attack in San Bernardino. I think the fbi would actually be more effective than some of our european colleagues were, at uncovering the rest of that network, if it existed, and disrupting possible plots. And again, that is the piece that is so shocking here, that despite the focus, despite the investigation over the past four months since paris, that this still occurred. And it occurred not in a small scale way, but in really a large scale, spectacular, and quite sophisticated way. Michael leiter, thank you for your honest answers yet again. Always good to see you. Thank you very much for being with us. At this point, we want to welcome Arizona Republican senator john mccain, chairman of the Senate Armed Services committee, member of the Homeland Security and Government Affairs committees. Senator, i was thinking earlier today, the war you fought in was considered so asymmetrical for its times, the way the United States arrived in vietnam, the length of time it took us to change to fit the fight. And yet, this is the most asymmetrical battle we have ever been faced with. The attacks are spectacular and gruesome. The good guys win, but often in the dark of night, and its often thanks to drones. Have you any doubt that were in a kind of slowrolling world war . I have no doubt about it. And i think, as you mentioned, its vastly asymmetrical. I understand that the attacks in paris cost Something Like 10,000. But i also would compare it to vietnam that we incrementally increased our effort there, which turned out to be a losing idea. We are incrementally increasing our presence in iraq and in syria and its not that were doing nothing, but its nothing that we have done has had any measurable effect. And i agree with everything that mr. Leiter said. But the problem is, brian, that there is a geographic base for this terrorist organization. Its called raqqah, and theyre training and equipping and theres even in news reports that they have a chemical weapons factory there in raqqah. And until we have a strategy to go in and take them out and kill them, theyre going to be exporting these attacks and these people, particularly in the flow of refugees, and they will be, unfortunately, there will be further acts of terror in europe and in the United States of america, because this president has no strategy to defeat isis. And isis a product, not of a tsunami or a hurricane, but because of a failed Foreign Policy that pulled all of our troops out of iraq, al qaeda metastasized into isis, and we did not go after them and the beat goes on. And now we are faced with the dimensions of a strategy of a threat that we are going to be with for a long time. I dont know if its curtis la may who gets credit for the term carpet bombing, but lets say we carpet bombed raqqah, an idea thats picking up some currency i would not do it is said you cant carpet bomb an idea out of existence, but what do you do about these cells . What do you do about the fact that these people are living in belgium . First of all, i would not carpet bomb. That that just would not be workable and would, in the longterm, i think, have very bad consequences for the United States. I would support strongly a force of about 100,000, with about 10,000 americans, composed of sunni nations, to go in, on the ground, in raqqah. And take them out. We are either going to kill them there, or were going to kill them in the United States of america in europe. It is not more complicated than that. But wed have to go in on the ground and liberty it. Carpet bombing would not be the answer. Now, if sophisticated drone strikes, et cetera would be, the efficient use of air power would be part of this, but you would have to go in on the ground, and the majority of those forces would be sunni arab, not u. S. Troops, although we would provide some of the vital elements of success. But as long as they have that base, and they will be able to export, especially through this flow of refugees, further attacks on europe and the United States of america, and mr. Mo m e moeller, the former deputy head of the cia in just the past couple of days said, and i agree with him, theyre winning. Their metastasizing in places like libya and africa and other places. Theyre not losing. So to that to the other point. Lets say you kill them in raqqah. Lets say you get your wish and theres a force of 100,000 and its very effective on the ground. What do you do about those living in brussels . Well, thats where you stop where the attacks originate. You cut off the head, and without that, the rest of the body dies. And the head of it is based in raqqah, syria, where they are planning, training and orchestrating these attacks. And you have to go after the head of the snake and then the rest of it will follow. And then, of course, youll still have radical islamic elements in the world, and we have a long struggle with that. But as long as they have a geographic base for a terrorist organization where they can plan, train, equip, and by the way, also develop chemical weapons, as they are now, according to news reports, then they will continue those attacks and those attacks will reach the United States of america. Decorated adequate veteran, former pouch. O. W. And a veteran senator from arizona, john mccain, good to have you on, sir. Thank you very much. Thank you. Richard engel is here in the studio with us, our chief Foreign Correspondent. Richard, first question to you, as to pick up on senator mccains answer to that question. Well, you do hear that theory a lot, that there needs to be a force to drive isis out of its safe haven. That they cant have a safe haven, not just in raqqah, but also mosul and many places in between. The problem is, whos going to be that force . Is it going to be american troops . Some component of american troops . The senator says 10,000 of them would be americans. I ask you that question. Would that be palatable in this country after the last decade of middle east entanglements . Im not so sure. And what does that do for those living in brussels and San Bernardino . So theres two elements of this. There needs to be some some force, as this is what experts tell me. And some of that force is being used, and john mccain and others, senator, dont think that enough force is being used. The other part is, how do you deradicalize the people who are living in brussels, in paris, in the United States, and elsewhere. And increasingly, im hearing people talk about an offramp. You need to give them an offramp. What does that mean . Let me use al qaeda as an example. Al qaeda was born it was backed everyone knows the history, by the cia. It was backed by pakistan. It was backed by the saudi government, in order to fight the soviets, it had a cold war purpose. And then the group was not just ignored, it was actually hunted down. Punished. When these people tried to go back to their homes in egypt or algeria, they were put on mass trials and sentenced to death. So you have Al Qaeda Al Qaeda became a Permanent Group of fugitives that had no place to go. And i like to think of al qaeda as this sort of disgruntled Veterans Organization that lived homeless, looking for foreign wars to join, because it couldnt go home. Isis is bigger. Isis is more entrenched already in society. So if you try and make them all permanently fugitives, you offer them no offramp, then the only alternative is to find every one of them and kill every one of them. And thats probably unrealistic. So i think it needs to be a combination of denying the terrain, fighting the ones who are determined to fight, and giving an offramp who decide that they dont want to do this anymore. By the way, having spent the number of years of your life you have covering these conflicts, i dont think you have to quote the experts. I think you can now qualify as one. And as that, how does this end . It ends, probably, with a solution in syria. Thats how it probably ends. When i was listening to senator mccain just a minute ago talking about a sunni arab force marching into raqqah, and i kept thinking, okay, well, how are the turks going to feel about that . And how are the kurds going to feel about that . And how is the Syrian Government going to feel about that . And how is iran going to feel about that . And russia . And thats all to have these questions remain unanswered in syria. So isis is thriving not because its so strong or because its ideology is popular. Its because there is no collective idea for what to do to solve the conflict, to solve iraq. To solve syria. You solve those problems, you reestablish governance in syria. You come up with a peace deal. Theres talks underway in geneva. You come up with a peace deal that works, then isis is an enemy to its own state, at this stage. Right now its thriving because there is no state. Richard engel, our chief Foreign Correspondent here with us, during home leave, oddly, for this attack, which is good for us, because we get to ask your opinion. Thank you very much. Good to be with you. Well take a break, and when come back, well go to correspondent chris dickey, longtime veteran journalist whos lived overseas for a long time. And being based out of paris, has now witnessed these last two terrorist attacks. When my doctor told me i have agerelated macular degeneration, amd we came up with a plan to help reduce my risk of progression. And everywhere i look. Im reminded to stick to my plan. 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We are back, covering todays awful terrorist attack in brussels, belgium. Our next guest is christopher dickey. He is, these days, the daily beast Foreign Editor and msnbc contributor. He has been posted overseas for many, many years, a veteran journalist, and i also should add, he has written beautifully about growing up in the american south. And chris, the problem is, you and i talk on television following Something Like this, lately, in the last few months, anyway. Is the belief there, that this attack, and forgive my wording, was a quite a few quick turnaround response to the arrest of the lone fugitive from the paris attacks . Well, there are a lot of theories, but i dont think any of the theories think that this was all pulled together, just in a couple of days, in the 3 1 2 days after the arrest of salah abdelslam, who was the last of the core eight members who carried out the paris attacks. When he was arrested, there was talk that he was involved with some other new plot. Maybe this was the plot that was already in the works. I think thats possibly likely. But at the end of the day, we dont know much about these people, who are who carried out the airport bombing. We know nothing about the person who carried out the metro bombing, in the metro station thats just behind me. And we know nothing about the person whos on the lam, except for the blurry picture of him. But what we do know is that they were very well organized, they had good logistical support, and that implies that theres a lot more of this out there. A lot more people like them and a lot more risks to come. I heard you earlier telling tamron hall that brussels tonight was kind of a blur of lights and sirens and vehicles going by your location quickly. For americans who dont know brussels, and youve been posted overseas for so long, how would you describe the city, and more importantly, how have you watched it change, say, over the last decade . Well, you know, brussels is a its a beautiful, but a slightly disorganized city. This is a kind of disorganized country. Half of it speaks flemish, the other half speaks french. It went without government for almost two years. And you always have the feeling that this is a, that somehow things dont quite gel in this town. At the same time, its the capital of europe. So, in fact, this metro station back here, the buildings that its in the middle of are the heart of European Union.