Details Inside the Threat Overseas

The State Department is now ordering all U.S. citizens out of Yemen because of terrorist activities there and growing civil unrest.

The embassy in Sana'a is being evacuated, except for essential personnel.

This comes on the heels of emerging details into what was behind a terror threat so specific, and so immediate that officials in this country decided to shut down nearly two dozen embassies and consulates across the Arab world.

 “The cascade of warnings and American embassy closures was triggered by an intercepted communication, which is now being revealed as a direct order from Al Qaeda's leader,” reports CNN’s Chris Lawrence reports.

“CNN has learned Ayman al Zawahiri ordered his new deputy in Yemen to basically 'do something,' and launch an attack. That deputy, Nasir al Wuhayshi, is now high on the US target list, along with another Yemeni, Al Qaeda's master bomb-maker Ibrahim al-Asiri.”

This set off extreme measures from Washington.

“On Monday senior Administration officials met to talk about a resurgent Al Qaeda,” Lawrence says.

 “US military and intel assets were being re-deployed around the world, in light of the new threat. Special operations teams have been placed on high alert overseas. Drone surveillance has been stepped up, and analysts are collecting more satellite images, trying to pinpoint a target.”

Follow along at CNN.com for developments.