Washington (CNN) -- The intercepted al Qaeda communications that sparked the closure of U.S. embassies in the Middle East and North Africa contained specific words that American intelligence interpreted as a coded message for what they believed signaled a potentially imminent attack, CNN has learned.
The coded words directly pointed to the likelihood of a significant al Qaeda attack against an overseas U.S. installation, according to a U.S. source familiar with the latest intelligence.
However, the words did not give clues as to a specific location or target, which is what led to closing nearly two dozen embassies and other diplomatic facilities deemed to possibly be at risk.
The U.S. intelligence community had been monitoring al Qaeda communications regularly, but was especially concerned about three intercepts.
The first was from Nasser al-Wuyhashi, the leader of al Qaeda in the Arabian Peninsula, outlining a possible attack. Another was Ayman al-Zawahiri's response to that from his position as leader of the global al Qaeda movement.
Two weeks earlier, the United States had also monitored a communication from Zawahiri appointing al-Wuyhashi as his deputy.
A U.S. official declined to discuss specific code words on the intercepts but told CNN "there was a sense of imminence, a sense of the overall area at risk and the known actors. There was great concern."
Members of Congress have indicated that National Security Agency surveillance programs played a role in intercepting and monitoring recent al Qaeda communications.
The programs were defended by Secretary of State John Kerry on Tuesday.
"A number of groups in the world have individually targeted not just American interests but free interests in the world," Kerry said during press conference in Brasilia, Brazil. "There have been bombings in many places in the world. Innocent people have lost their lives. And what the United States has been trying to do is prevent these things from happening beforehand by knowing what others might be plotting."
Separately, a Yemeni official told CNN that a recent drone strike did not injure suspected AQAP bombmaker Ibrahim al-Asiri contrary to an earlier Yemeni news agency report that said he might have been hurt.
Three suspects on Yemen's list of its 25 most-wanted terrorists have been captured and two others killed recently, according to the official. It is not clear if those outcomes were the result of drone strikes or other operations.