Top U.S. officials on Sunday said the exact nature of the suspected al Qaeda threat that temporarily shuttered key U.S. diplomatic posts across the Middle East and North Africa remains unclear, and that intelligence suggests the "significant" event could mean either one large attack or simultaneous attacks across the globe.
Meanwhile, officials late Sunday said 19 embassies and consulates would remain closed through next Saturday.
Officials told NBC News that the threat appears to be linked to Yemen, but State Department spokespeople have only confirmed that the warnings are generally tied to al Qaeda.
Yemen is home to perhaps the most dangerous terror network affiliate, known as al Qaeda in the Arabian Peninsula (AQAP). The lethal wing is considered responsible for several terrorist strikes on the United States, including the foiled Christmas Day 2009 attempt to bomb an airplane over Detroit.
Some European countries — including Britain, Germany, and France — temporarily shut down their embassies in Yemen as officials moved to tighten security.
Security officers and soldiers blocked roads outside Western embassies in the capital of Sanaa Sunday, only allowing residents through following thorough inspections, while troops with automatic rifles were on hand outside the French embassy, according to Reuters.
"There is a high level of coordination with the American side, and these measures have been taken due to fears of attacks by al Qaeda," a Yemeni security official told Reuters.
On Sunday, the State Department announced that "out of an abundance of caution," the closure of several embassies and consulates would be extended.
"Given that a number of our embassies and consulates were going to be closed in accordance with local custom and practice for the bulk of the week for the Eid celebration at the end of Ramadan, and out of an abundance of caution, we've decided to extend the closure of several embassies and consulates including a small number of additional posts," spokeswoman Jen Psaki said in a statement.
"This is not an indication of a new threat stream, merely an indication of our commitment to exercise caution and take appropriate steps to protect our employees including local employees and visitors to our facilities."
The closure extensions week include 15 posts that were already closed Sunday and four additional posts.
Posts in Abu Dhabi, Amman, Cairo, Riyadh, Dhahran, Jeddah, Doha, Dubai, Kuwait, Manama, Muscat, Sanaa, Tripoli, Antananarivo, Bujumbura, Djibouti, Khartoum, Kigali, and Port Louis are instructed to close for normal operations Monday, August 5 through Saturday, August 10, the State Department said.
U.S. offices in Algiers, Baghdad, Kabul and six other cities are authorized to reopen Monday.
Meanwhile, U.S. lawmakers on both sides of the aisle made the rounds on Sunday morning talk shows to shed light on the threat.
The threat represents the most serious in years and harkens back to the “chatter” that preceded the Sept. 11, 2001 attacks, a top Republican lawmaker said Sunday, as officials at nearly two dozen U.S. embassies tightened security.
“The one thing we can talk about is the fact that there’s been an awful lot of chatter out there,” Sen. Saxby Chambliss (R.-Ga.), the ranking member of the Senate Intelligence Committee, said Sunday morning on NBC’s “Meet the Press.” He added that the chatter is “very reminiscent of what we saw pre-9/11.”
“This is the most serious threat that I’ve seen in the last several years,” Chambliss said.
Rep. C.A. Dutch Ruppersberger (D-Md.), the top Democrat on the House Intelligence Committee, told ABC’s “This Week” that the threat information intercepted from “high-level people in al Qaeda in the Arabian Peninsula” concerned a “major attack.”
Rep. Peter King (R-N.Y.), who heads the House Homeland Security subcommittee on counterterrorism and intelligence, told ABC that “al Qaeda is in many ways stronger than it was before 9/11, because it’s mutated and it spread and it can come at us from different directions.”
“The threat was specific as to how enormous it was going to be and also that certain dates were given,” King said.
Rep. Adam Schiff, a House Intelligence Committee member, said the “breadth” of the embassy closures indicates that U.S. authorities are defending against a potential repeat of last year’s riots and strikes at multiple U.S. embassies, including the deadly attack on the post in Benghazi, Libya, where U.S. Ambassador Christopher Stevens and three other Americans were killed.
What’s more, Interpol, the French-based international police agency, has issued a global security alert in relation to suspected al Qaeda involvement in various recent prison escapes, including those in Iraq, Libya and Pakistan.
“So you have a lot of things coming together. … But all of that would not be enough without having some particularly specific information,” Schiff told The Associated Press.
The Obama administration announced the weekend closures on Friday, and the State Department later released a global travel warning.
The alert called on American travelers to take additional precautions overseas, pointing to potential dangers involved with public transportation systems and other likely locations for tourists. It said that previous terrorist attacks have targeted subway and rail networks as well as airplanes and boats.
The alert is slated to expire Aug. 31.
The threat intelligence also arrives ahead of the Eid celebration at the close of the Muslim holy month of Ramadan later this week and nearly a month prior to the 12-year anniversary of the Sept. 11, 2001 attacks on the United States.
President Barack Obama, fresh off his birthday celebration at Camp David, returned to the White House at 2:00 p.m. Sunday. He has been briefed throughout the weekend on the evolving terror threat, including a Saturday exchange with counterterrorism adviser Lisa Monaco.
Officials who spoke to NBC News said that while there is no known specific threat targeting the U.S. homeland, they cannot rule out the possibility given the broad scope of the suspected threat.
The New York Police Department added additional officers and critical response cars to their counter terrorism teams in response to the overseas security threat, according to NBC New York. The NYPD also plans to escalate security at religious facilities and other sensitive areas throughout the city.
Meanwhile, the U.S. Capitol Police and chief of the District of Columbia Metropolitan Police Department reminded employees Friday to remain vigilant.
Reuters and The Associated Press contributed to this report.