Threat from al-Qaida leaders that closed US embassies was discussed in online jihadi chat room

U.S. intelligence officials say the terror threat that closed 19 diplomatic posts across Africa and the Middle East was discussed on an online jihadist forum and consisted of an unspecific call to arms by al-Qaida's top leaders.

Experts say it's highly unlikely that al-Qaida's top leader, Ayman al-Zawahri, or his chief lieutenant in Yemen, Nasser al-Wahishi, were personally part of the Internet chatter.

Instead, it's believed the messaged threat was sent from the leaders through couriers to tech-savvy underlings and ultimately to the attackers who were gathered on a highly secretive and encrypted online forum within the past month.

It's not clear how U.S. officials detected the plot.

The intelligence officials spoke on condition of anonymity because they were not authorized to discuss the threat publicly.