WASHINGTON — The Obama administration’s decision last week to close nearly two dozen diplomatic missions and issue a worldwide travel alert resulted from intercepted electronic communications in which the head of Al Qaeda in Pakistan ordered the leader of its affiliate in Yemen to carry out an attack as early as this past Sunday, according to US officials.
The conversations last week were between Ayman al-Zawahri, who succeeded Osama bin Laden as the head of the global terrorist group, and Nasser al-Wuhayshi, the leader of the Yemen-based Al Qaeda in the Arabian Peninsula, the group’s most lethal branch.
The intercepts revealed one of the most serious plots against United States and other Western interests since the attacks on Sept. 11, 2001, US intelligence officials and lawmakers have said.
Intelligence analysts on Monday were combing e-mail, phone calls, and radio communications between Al Qaeda operatives in Yemen and the organization’s senior leaders to determine the timing and targets of the planned attack.
It is highly unusual for senior Al Qaeda leaders in Pakistan to discuss operational matters with the group’s affiliates, so when the intercepts between the two senior Al Qaeda leaders were collected and analyzed last week, senior officials at the CIA, the State Department, and the White House immediately seized on their significance.
Members of Congress were quickly provided with classified briefings on the matter, US officials said.
“This was significant because it was the big guys talking, and talking about very specific timing for an attack or attacks,” said one US official who had been briefed on the intelligence reports.
The identities of the two Al Qaeda leaders whose discussions were monitored and the imminent nature of the suspected plot — in the intercepts, the terrorists mentioned Sunday as the day that the attacks were to take place — help explain why the United States, as well as other Western governments, have taken such extraordinary precautionary steps to close embassies and consulates in the Middle East and North Africa.
But the intercepts were frustrating in that they did not reveal the specific location or target, US officials said.
In an article posted on the Web Friday and published Saturday, the identities of the Al Qaeda leaders whose conversations were intercepted were withheld by The New York Times at the request of US intelligence officials. The names were disclosed Sunday by McClatchy Newspapers, and after the government became aware of the article, it dropped its objections to The Times’ publishing the information.
US officials have not said whether the CIA, the National Security Agency, the Defense Intelligence Agency, or another agency intercepted the initial suspect communications.
The Associated Press, quoting an unidentified intelligence official, said Monday that the controversial NSA programs that gather data on American phone calls and track Internet communications with suspected terrorists played no part in detecting the initial tip.
The State Department said Sunday that it was extending the closure of 19 diplomatic posts in the Middle East and North Africa through at least next Saturday because of continued fears of an imminent attack. Several European countries have also closed embassies in the Middle East.
A State Department spokesman said the closings were not the result of new threat intelligence, but “merely an indication of our commitment to exercise caution and take appropriate steps to protect our employees and visitors to our facilities.”
The embassies that will be closed include the ones in Yemen, Libya, Egypt, Saudi Arabia, and the United Arab Emirates, the statement said.
The US Embassy in Pakistan has remained open, even though the Al Qaeda threat that shuttered many other diplomatic missions emanated in part from that country. Still, rumors of an impending militant attack on Islamabad, the capital — and not necessarily on a US target — coursed through diplomatic and security circles last weekend.
One Western diplomat, speaking on the condition of anonymity, said his mission had received reports that militant attackers had congregated in the Margalla Hills, which overlook the city. But the diplomat stressed that those reports were unconfirmed, and that although the security situation in the city had tightened, there was little information to suggest an impending assault.
Administration officials and intelligence analysts said Monday they had no new information on the terrorist threats.
“We are going to keep evaluating information as it comes in, keep analyzing the various intelligence that we’re getting in, in regards to this stream,” said a State Department spokeswoman, Marie Harf. “Overall, what we are doing is taking precautionary steps out of an abundance of caution to protect our people and our facilities and visitors to those facilities overseas.”
Members of Congress who were briefed on the threat said there was no definitive information on where an attack would occur.
“The assumption is that it’s probably most likely to happen in the Middle East,” Representative Peter T. King, a New York Republican, said Sunday on the ABC News program “This Week.” “But there’s no guarantee of that at all.”
“It could basically be in Europe, it could be in the United States, it could be a series of combined attacks,” said King, who is a member of the House Intelligence Committee.
The one aspect of the intelligence that officials appear to agree on is that Al Qaeda’s affiliate in Yemen is behind the plotting.