Top diplomats from more than a dozen countries dealing with whats been described as a, quote, bleak global environment. And its the situation in syria and the european refugee crisis that are overshadowing their talks. The meetings come just days after ministers from the United States, from russia and other nations all announced that theyve agreed to a pause in the fighting in syria to take effect in a week. But there are fears that at least two issues will scuttle any lasting peace in that nation. The continued russian airstrikes on aleppo and the insistence by the syrian president , Bashar Al Assad, that he would continue fighting enemies that he deems terrorists. Lets get the very latest from munich. Our Cnn International diplomatic editor, Nic Robertson, is live for us this hour. Nic, good to have you with us. So theres so many issues that are playing out in the world. What is the mood there among leaders in munich . Reporter well, theres concern about this peace plan for syria at the moment. The focus for the concern would be this next week in aleppo. Its very clear to the leaders here that russia and president Bashar Al Assad have a military agenda to achieve in and around aleppo. They feel that theyre making progress on that. Theyve got momentum. And so the International Syria support group that met here on thursday that agreed across the board that there should be a cessation of hostilities that should come into place next week. The concern is what happens in and around aleppo this week. Now, weve heard already this morning that the french Prime Minister has asked his russian counterpart, medvedev, to halt russias bombing. The concern at the moment is that if russia continues an aggressive Bombing Campaign in a week at the end of which everyone has agreed theres a cessation of hostilities, that will create a mood on the ground among the opposition, among the people of syria that means it will be very hard to restart peace talks over the next few weeks, which is what the agreement was anticipated to do. So theres a broad concern obviously about the security implications that so many refugees, not just from coming from syria, but a lot from syria, afghanistan and other countries coming into europe about the security implications for that, the security implications for the growth and spread of isis, relations with china and north korea is an issue here. But i have to say, the big talk at the moment between the leaders is concern about getting through this next week in and around the city of aleppo. Nic, i want to also talk about the continued bombing by russia. We just mentioned at the top of the show that the syrian president says that he is open to peace talks. But that he will continue to focus on groups that he deems to be terrorists. Also russia continuing its Bombing Missions against isis and the al nusra front which are not mentioned in that cessation of hostilities. So how can peace be achieved if that continues . Reporter the idea of the Peace Initiative is to get the opposition and the government speaking and agree to a new constitution and elections in 18 months time. Isis and al nusra have been designated by the u. N. And by the groups here as the terrorist elements. In the past russia has said that its targeted in its bombing isis and al nusra, the al qaeda affiliate, and theres been a lot of evidence to suggest on the ground that theyve been targeting the moderate opposition as well that fights president Bashar Al Assad but is supported by the United States, by turkey, by saudi arabia, by a lot of other countries. So theres been a very clear delineation now at this meeting in munich at the International Syria support group about who and what the terrorists are. If you will, that gives russia less scope to target those that arent isis and al nusra. It remains to be seen if they do stick to that new definition, and thats certainly something that theres going to be pressure now on the Syrian Government to stick to while president Bashar Al Assad says hell continue to fight terrorists. The terms of the agreement state quite clearly that you can no longer call the opposition, who hes supposed to be talking to, the terrorists now. So thats been a change. Its not clear if the sides are going to stick to that, but thats been a very clear change, and its also up to the United States and russia together, leading the military task force thats come out again of this munich meeting to determine where isis is, where al qaeda, al nusra front is, and then target them. So both russia has a legitimate reason to be targeting isis and al qaeda. Thats an expectation the fight is going to be taken to them. That the United States and the coalition also are going to be taking the fight to al qaeda and al nusra, that the government would, too, and the opposition thats supported by the west and by the arab allies also will be fighting isis and al qaeda. So the fight is going to be, the hope, focused on isis and al qaeda. The real radical islamists. There are fringes of that, of those groups, and in places who have had alliances with rebel groups. That complicates it. But at a simple level, thats whats supposed to happen. The government and the opposition, this broad opposition, are supposed to sit down and talk, but the fight against isis and al qaeda remains. It is a complicated puzzle as these World Leaders try to find peace in that region. Cnn International Diplomatic editor Nic Robertson live for us at the security conference in munich. Nic, thank you. The Syrian Government forces have made major gains across the northern part of syria. But, of course, theyre getting the help, the backing, of russian air power. Cnn has gained unusual access in areas just north of aleppo that have been taken back by assad loyalists. Our Fred Pleitgen is in a town that has endured years of fighting and has this exclusive report. Reporter god, syria, bashar and nothing else these villagers chant, in the proregime village. The mostly shia town was under rebel siege for more than three years. 14yearold lived through it and recalls the hardship. It was very tough, he says. Many people got sick, and the kids were very scared. But after a while, we became numb to the fear. The siege was broken by the recent government offensive north of aleppo. Now there is food in the local markets and clearly a lot of support for the main backers of the assad regime, hezbollah, iran and russia. The people here are keen to show their affection for hezbollah, iran and russia. They believe that throughout the years of siege, its these groups who stood by them and ensured this towns survival. The u. N. Has strongly criticized the denial of aid to besieged areas in syria, accusing Government Forces, some rebel groups, and isis of using food and medicine as weapons. A new agreement reached by world powers hopes to put an end to these tactics. Aleppos countryside is now one of the main battlegrounds in this brutal fiveyear civil war. As proGovernment Forces press an offensive backed by russian air power, tens of thousands have fled towards the turkish border. On our trip, we saw scores of deserted villages, some clearly scarred by fierce fighting. Government soldiers issued a strong warning to opposition fighters. Their families encouraged them to look for reconciliation. Otherwise they will be killed. They have no other option. But the opposition believes reconciliation is not on the governments mind. They say they are simply being slaughtered as the Syrian Military continues to push to try and retake the area north of aleppo in what many feel could be a crushing blow to antiassad forces. Fred pleitgen, cnn, syria. Many syrians are still trying to get out of harms way. Tens of thousands of refugees have fled north toward turkeys border with syria. Arwa damon has more on their plight and the effort to get aid to syrias hardesthit cities. Reporter despite the agreement of a cessation in hostilities, aid organizations are continuing to try to send in as much assistance to various areas in the country but especially to aleppo. Many of them still fearing and concerned about the fate of the civilians there and the fact that the Syrian Regime is very close to besieging aleppo. Aid organizations like mercy corps say that they are dispatching inasmuch as three months worth of supplies. Meanwhile, tens of thousands of those trying to flee the violence continue to gather on turkeys border. Turkey, despite the fact that it maintains that it still has an opendoor policy, says that for the time being it is hosting those who have fled this most recent onslaught by syrian fighter jets and regime troops advancing along with their allies inside syria, saying that it is providing the same conditions for them that it would be providing at refugee camps inside turkey. But, of course, the concern is that as these russian fighter jets approach the various cities and towns closer to turkeys borders, as the regime gains even more territory, these civilians do remain very vulnerable to the violence. And as long as they are in syria, that one thing that they really so desperately crave, that sense of security is denied to them. Arwa damon, cnn, turkey. Many refugees have to resort to human traffickers to help escape from war zones. A little later in our show, our phil black takes us on a navy ship used in the fight to put a stop to trafficking. He shows us how they train to catch smugglers in action. Pope francis, he is in mexico this hour. And, of course, he landed friday night to a rockstar greeting. Hundreds of cheers and chants for the first latin american pope. The president met with francis at his plane and will have an official visit in a few hours time. Earlier friday, the pope met with russian patriarch in cuba, a meeting that was a millennium in the making. This was the first time a pope met with the head of the Russian Orthodox church since the two faiths split in 1054. Pope francis has a full schedule while in mexico. And as typical of his visits, the pope will spend a great deal of time ministering to the poor. Shasta darlington has more on what we can expect to see over the coming days. Reporter some surprisingly melodious parishioners gearing up for Pope Franciss arrival. A sixday trip that starts right here. A basilica of the virgin of guadalupe, the patron saint of mexico. Visited by millions of pilgrims each year. Who pray before a 16th century shroud that bears her image. According to the chaplain, pope francis seeks guidance at the start of his trip. Hes looking for her protection, he says. Hes entrusting his whole trip to mexico to the virgin of guadalu guadalupe. Pope francis planning to visit some of mexicos poorest and most violent corners. From a sprawling suburb with the highest rate of killings of women to the center of mexicos narco war. Pope francis chose this shrine because its the most revered. But its interesting, talking to parishioners here, they say of course they want to hear his message of faith, but theyre just as interested in having him shine a light on the problems of corruption and crime in mexico. I would ask him to talk to authorities about the violence, says this woman. Especially the disappearances. This man traveled on foot for five days to reach the shrine. The popes going to visit the places where people need him most, he says. Where he needs to motivate them so they dont lose faith. But here at the basilica, faith runs deep. For these musical nuns flying in from peru, the message is simple. When the future seems uncertain and fear weakens your faith, believe in god. Shasta darlington, cnn, nextco city. Mexico city. You are up with aing cnn newsroom. And still ahead, we have much more on the popes visit to mexico including a secret that he told our rosa flores on board the papal plane. That is coming up. Plus, president ial hopeful jeb bush hasnt been doing very well in the polls, but hes hoping now that a little help from his big brother will help to change that. Stay with us. Want to survive a crazy busy day . Sfx cell phone chimes start with a positive attitude. And positively radiant skin. Aveeno® positively radiant moisturizer. With active naturals® soy. Aveeno® naturally beautiful results®. This year alone, an estimated 80,000 refugees have landed in europe. The eu military is trying to curb the flow of migrants who are making that dangerous journey by sea into europe. Their goal is to target human traffickers. Cnns phil black has been on a war ship off the libyan coast to find out more about the mission. Reporter weve been at sea in the mediterranean with italian and Spanish Naval forces for five, six days now. This is part of the eu Naval Operation against people smugglers operating out of libya. We started when we were first transferred to the command ship for this entire operation. It is big. Its pretty new, and its really very impressive. From there, we came here, the spanish frigate. In pretty big seas, weve been carving through the south. These conditions here have been too big, the swell too rough, the winds too strong for people smuggling boats to put to sea. So in the meantime, the crew of these vessels, they need to train. And so we witnessed the marines aboard the ship conduct a boarding exercise. The marines are the ones responsible for making the approach to the migrant vessels. Giving a security assessment, making sure that there is no threat. During our time at sea, we spent a lot of time clambering in and out of helicopters. Aboard the helicopter here, we were able to get very, very close to the libyan border. Through the haze, you can see the libyan coastline in the distance. Were 12 nautical miles away at the very edge of libyan territorial waters. This is as close as these forces can get to where the people smuggling operations are based. Living aboard a frigate built in the 1980s, the late 1980s, it takes some getting used to, but its also really good fun. At least for a few days in the way that were doing it. But you get a real sense of what a challenging environment this would be to live in in the long term. So it is, of course, incredibly narrow. The confined space, we got lost a few times. Actually, were on the wrong deck. The hallways narrow, passing people all the time. Buenos diaz. We were warned that the single most dangerous thing aboard the ship are these narrow, steep ladders and stairs that separate the decks. And this is where they control the ship. And its a pretty extraordinary view. To get a sense of where this ship has been operating, where we are, what were waiting for, this is a map of the Southern Area of the mediterranean. Im not allowed to show you the coast of libya, but the people who run the operation, they talk about the triangle. If you imagine the coast of libya down here, there is tripoli on the eastern side. To the left heading towards the border with tunisia. It is from here the boats leave and head out north. Thats the trianglear shape more towards the center of the map. So today as the ship has been plowing through seas much bigger than what you see here now, this is pretty flat. The winds are pretty gentle by comparison. Theyve come down a long way. This, the crew believes, makes it more likely that youre going to see some sort of migrant boat movement. But where weve been positioned for a couple of days now, weve been holding a pattern to the northwest of tripoli probably just to the northwestern side of the libyan coast in international waters, waiting here in a position the crew beliefs is beyond the detection of the people smuggling crews and operators back on the libyan coast itself. We will arrive at 15 nautical miles. Reporter this is one of the marines stationed aboard a 50caliber weapon trained on the side. Is he looking out and ready for the possibility of some sort of attack from a smaller vessel. What the Commanding Officer describes as a terrorist attack. Now to the race for the white house. U. S. Republican candidate donald trump is threatening to sue his rival, ted cruz. Trump sent out this tweet earlier, threatening to take cruz to court over whether hes a natural born u. S. Citizen. That is if the texas senator doesnt stop running negative ads against him. Trump is questioning cruzs eligibility to become president since he was born in canada. The Cruz Campaign hit back, saying that trump needs to go to the, quote, timeout chair and think about his choices. Fellow republican candidate jeb bush has been struggling in the polls but is now getting a little help from his big brother. That would be the former u. S. President , george w. Bush, who will be campaigning for his brother in the state of South Carolina this week. Cnns athena jones has this report. I know jeb. Reporter george w. Bush is back. Experience and judgment count in the oval office. Jeb bush is a leader who will keep our country safe. He respects the military. He honors their families. Reporter and jeb bush couldnt be happier about it. Hes the last republican that was president. He is the most popular republican alive. Im a proud brother of george w. Bush. Reporter bush, Whose Campaign logo doesnt even include his famous last name and who began his run stressing he would be, quote, his own man has been embracing his family more with each passing day. Im jeb exclamation point proud to be a bush. Reporter his mother, barbara, joining him on the stump in New Hampshire. Have you met barbara bush . Reporter the brothers will be campaigning together for the first time monday. Until now, w. Has been helping out behind the scenes. This is the first time that hes really kind of stepped out in the political realm since he was president. I think there will be a lot of interest in what he has to say. Reporter it was once the younger bush who was thought to have a head for politics, but his olde