An official who’d been briefed on the matter in Sanaa, the Yemeni capital, told McClatchy that the embassy closings and travel advisory were the result of an intercepted communication between Nasir al-Wuhayshi, the head of the Yemen-based Al Qaida in the Arabian Peninsula, and al Qaida leader Ayman al Zawahiri in which Zawahiri gave “clear orders” to al-Wuhaysi, who was recently named al Qaida’s general manager, to carry out an attack.
Also, the threat information likely came not just from chatter and electronic surveillance, but human sources. Via CNN (linked above)
U.S. officials cautioned that there may be multiple sources of intelligence, including intercepts of electronic information from phone calls and web postings and the interrogation of couriers or other operatives.
Days before the announcement of the threat and closures, President Obama met with Yemen President Abd-Rabbu Mansour Hadi at the White House. I wonder if it wasn't Hadi who got the threat information from Yemen's national security forces and passed it on to Obama, resulting in the NSA NSA checking chatter to confirm. The human sources seem to be in Yemen. Whose sources are they -- Yemen's or the U.S.?
Here's a rough timeline of events.
There were a lot of al Qaeda statements issued in July. Some provided confirmation that al Sheri was killed in a drone strike (although the statements didn't say when and it had been months since the last report of his death.)
There were also reports of several drone strikes last week in Yemen killing AQAP members and others.
If anyone wants to read the English translations of some of the recent al Qaeda statements you can find them at Jihadology here. Examples:
