chunk: The CIA puts the compound under heavy surveillance for several months, using a variety of methods. Although they are confident from circumstantial evidence that bin Laden is there, they cannot prove this photographically. Meanwhile, the President's National Security Advisor tasks the CIA with producing a plan to capture or kill bin Laden if it can be confirmed that he is in the compound. An agency team devises a plan to use two top-secret stealth helicopters (developed at Area 51) flown by the Army's 160th Special Operations Aviation Regiment to secretly enter Pakistan and insert members of DEVGRU and the CIA's SAD/SOG to raid the compound. Before briefing President Barack Obama, the CIA Director holds a meeting of his top officials, who assess only a 60–80% chance that bin Laden, rather than another high-value target, is living in the compound. Maya, also in attendance, states the chances are 100%.