. >> reporter: mosul, now an isis stronghold in iraq. last week, this man who said he's an isis defector, provided nbc news with a cache of documents he claimed he stole from the group. the documents show foreign fighters have to obtain permission to leave with each logged in these forms. isis may be starting to lose its grip on its territory. last week a u.s. official said isis had retreated from 1,000 square miles. both the leaking of information and today's bizarre desertion show that isis may be cracking under the pressure from its many enemies. a u.s. law enforcement official said quase was apparently not not a u.s. database of suspected isis members who have traveled overseas. in other words, they didn't know he had gone to fight with isis until he got caught trying to sneak out. lester? >> richard engel, tonight. >>> a surprise announcement today from russian president vladimir putin who says he's withdrawing most of russian troops from syria charging their mission has been accomplished. putin sent forces in in october with a stat

the life in mosul, bad. >> reporter: he said he realized his mistake in joining isis. u.s. officials say the group is having trouble keeping its recruits, and that he could be of intelligence value. >> amazing to see him speaking so openly. richard, thank you very much. >>> president obama's nominee for the supreme court, merrick garland, made his first visit to capitol hill today hoping to meet with as many senators as he can. but he's had no meetings with republicans yet. some now say they're open to the idea. but the gop appears to be standing firm on denying him a vote. nbc's pete williams went to get answers on the hill. >> reporter: they're known as courtesy calls, merrick garland may find courtesy in short supply at the senate. so far democrats have formally agreed to meet with him, including harry reid and patrick leahy. highlighting their meetings to push for a hearing in a vote, though republicans say neither will happen. do you think that could be changed? >> i hope it will be changed. because i cannot imagine any senator standing up and saying, i'm not going to

iraqi troops are preparing for an assault on mosul, a large city that has been held by isis for almost two years. >>> two americans were killed, at least among the four people in a suicide bomb attack in turkey today. it happened in istanbul in the middle of a shopping district. last week, another attack left 35 people dead in the capital. three dozen people were injured in today's explosion. >>> the stop trump campaign heated up today in arizona as the republican front runner campaigned in that state which holds its primary tuesday. immigration is a key issue. the latest tonight in hallie jackson in arizona. >> reporter: stopping traffic, hoping to stop trump, protesters filled this phoenix and arrests, arguments. again, after these angry scenes in salt lake city last night. his supporters line up for trump's rallies in arizona, ground zero for the political battle over immigration. today, trump appearing with the governor and and a sheriff. >> this country has a big, big problem with illegal immigration. >> reporter: he is ramping up attacks on mitt romney after he said he would vote