intended, there are a lot of animals that live across that wall, too. they want to make sure there is space between the wall so they can have the migration of animals if not the migration of people. >> there are rivers over there, over the border. will they have employees to build it. plenty of issues. the u.s. taking action the first time based on intelligence recovered in the january raid in yemen that killed a navy seal. they are looking to track and locate hundreds of people with ties to al qaeda. those contacts were part of the recovered intelligence. some of these people are believed to be in the west, though not in the united states. cnn's barbara starr with more now from the pentagon. >> reporter: dave, christine, u.s. officials are insisting to cnn that they did get valuable intelligence from that raid back in january that killed the u.s. navy seal and led to the death of several civilians on the ground. none of them can be absolutely verified because the intelligence is classified. but officials say that they are now taking action to monitor,