correspondent identivan watson more. >> reporter: the u.s. vessel is supposed to be an an fib louse assault vessel but it's providing air, sea and land support to puerto rico and the islands. it's got a fleet of helicopters and vert tal takeoff ospreys, shuttling trucks and bulldozers and a water desail linization unit to puerto rico. providing drinking water. the department of defense tells cnn they have about 2500 active duty troops on the ground and expecting to nearly double that in the kays to come. le but that simply may not about enough for an island of 3.4 million people, where transport, lelectricity and