One lawmaker said the chatter was specific as to certain dates and the scope of the operation; others said it suggested that a major terrorist attack, akin to 9/11, was being planned by the al-Qaida affiliate in Yemen.
Diplomatic facilities will remain closed in Egypt, Jordan, Libya, Yemen, Saudi Arabia and Kuwait, among other countries, through Saturday, Aug. 10. The State Department announcement Sunday added closures of four African sites, in Madagascar, Burundi, Rwanda and Mauritius. The U.S. reopened some posts on Monday, including those in Kabul, Afghanistan and Baghdad.
Last week the State Department announced a global travel alert, warning that al-Qaida or its allies might target either U.S. government or private American interests. It said Americans should take extra precautions overseas and cited potential dangers involved with public transportation systems and other prime sites for tourists.
Spokeswoman Jen Psaki said the decision to keep certain embassies and consulates shuttered throughout the week was done out of an "abundance of caution" and to "protect our employees, including local employees, and visitors to our facilities."
Sen. Richard Blumenthal, D-Conn., a member of the Senate Judiciary Committee, said Monday the briefings he has received "certainly emphasize these threats are specific and credible, equal if not more serious to the kind of chatter, as the intelligence called it, that was heard prior to 9/11."
But he added: "The average American should continue to be alert and vigilant and cautious but certainly not unduly alarmed or panicky." He spoke on MSNBC.
The intercepted intelligence foreshadowing an attack on U.S. or Western interests is evidence of one of the gravest threats to the United States in years, said several lawmakers said Sunday.
Sen. Saxby Chambliss of Georgia told NBC's "Meet the Press" that the conversation was "very reminiscent of what we saw pre-9/11." Chambliss, the top Republican on the Senate Intelligence Committee, said it was that chatter that prompted the Obama administration to order the closures and issue the travel warning.
Rep. C.A. Dutch Ruppersberger of Maryland, the top Democrat on the House Intelligence Committee, told ABC's "This Week" that the threat intercepted from "high-level people in al-Qaida in the Arabian Peninsula" was about a "major attack."
Yemen is home to al-Qaida's most dangerous affiliate, blamed for several notable terrorist plots on the United States. They include the foiled Christmas Day 2009 effort to bomb an airliner over Detroit and the explosives-laden parcels intercepted the following year aboard cargo flights.
Rep. Peter King, the New York Republican who leads the House Homeland Security subcommittee on counterterrorism and intelligence, told ABC that the threat "was specific as to how enormous it was going to be and also that certain dates were given."
The Obama administration's decision to close the embassies and the lawmakers' general discussion about the threats and the related intelligence discoveries come at a sensitive time as the government tries to defend recently disclosed surveillance programs that have stirred deep privacy concerns and raised the potential of the first serious retrenchment in terrorism-fighting efforts since Sept. 11.
Senate Judiciary Committee Chairman Patrick Leahy, D-Vt., has scoffed at the assertion by the head of the National Security Agency that government methods used to collect telephone and email data have helped foil 54 terror plots.
Rep. Adam Schiff, D-Calif., a House Intelligence Committee member, said while he takes the threat seriously he hasn't seen any evidence linking the latest warnings to that agency's collection of "vast amounts of domestic data."
Other lawmakers defended the administration's response and promoted the work of the NSA in unearthing the intelligence that led to the security warnings.
King, a frequent critic of President Barack Obama, said: "Whether or not there was any controversy over the NSA at all, all these actions would have been taken."
The State Department noted that previous terrorist attacks have centered on subway and rail networks as well as airplanes and boats. It suggested travelers sign up for State Department alerts and register with U.S. consulates in the countries they visit. The alert expires Aug. 31.
The intelligence intercepts also prompted Britain and Germany to close their embassies in Yemen on Sunday and Monday. British authorities said some embassy staff in Yemen had been withdrawn "due to security concerns." France said Monday it would keep its embassy in the Yemeni capital closed through Wednesday.
Interpol, the French-based international policy agency, has also issued a global security alert in connection with suspected al-Qaida involvement in recent prison escapes including those in Iraq, Libya and Pakistan.
Associated Press writer Michele Salcedo contributed to this report.
Copyright 2013 The Associated Press.