The State Department issued a worldwide travel alert on Friday to U.S. citizens over an Al Qaeda terror threat as Washington prepared to close its embassies and consulates throughout the Muslim world this Sunday over security concerns.
U.S. officials have not offered many details on the nature of the threat, but apparently are taking it seriously.
A White House official said Friday night President Obama was being updated on "a potential threat occurring in or emanating from the Arabian Peninsula."
"There is a significant threat stream and we're reacting to it," said Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff. He told ABC News in an interview to be aired Sunday that the threat was "more specific" than previous ones and the "intent is to attack Western, not just U.S. interests."
John Bolton, former U.S. ambassador to the U.N., said the alert indicates the U.S. government must have some "pretty good information" about a possible threat.
Great Britain announced Friday night it would also close its embassy in Yemen "as a precautionary measure" on Sunday and Monday and urged its nationals to leave the country.
The travel alert issued Friday warned Americans of the "continued potential for terrorist attacks, particularly in the Middle East and North Africa, and possibly occurring in or emanating from the Arabian Peninsula."
It said: "Current information suggests that al-Qa'ida and affiliated organizations continue to plan terrorist attacks both in the region and beyond, and that they may focus efforts to conduct attacks in the period between now and the end of August."
The alert reminded Americans about the potential for attacks on transit systems and other "tourist infrastructure."
Pentagon officials also said there is an increased alert among security personnel in the region in response to the Al Qaeda terror threats.
"Actions have been taken," one Pentagon official told Fox News.
Retired Gen. Jack Keane, a Fox News military analyst, said the threat is yet another sign that Al Qaeda and its affiliates are emboldened -- and stressed that the U.S. needs to do a better job securing its embassies.
"It has got to be one of our top priorities," he told Fox News.
Keane said it appears Al Qaeda is trying build off the Benghazi terror attack. "When they sense weakness, they attack," he said. "They believe that we're pulling back, and they were stunned ... that we did not come after them immediately after that attack."
State Department officials said Thursday, after announcing the temporary shutdown of embassies and consulates on Sunday, that they were acting out of an "abundance of caution."
Spokeswoman Marie Harf cited information indicating a threat to U.S. facilities overseas and said some diplomatic facilities may stay closed for more than a day.
Sunday is a normal workday in many Arab and Middle Eastern countries, meaning that is where the closures will have an impact. Embassies in Europe and Latin America would be shuttered that day anyway. The State Department on Friday released a list of 21 embassies and consulates affected.
"We have instructed all U.S. embassies and consulates that would have normally been open on Sunday to suspend operations, specifically on August 4," a senior State Department official said Thursday night. "It is possible we may have additional days of closing as well."
Other U.S. officials said the threat was specifically in the Muslim world.
The issue of security abroad has been prominent since the attack on the U.S. compound in Benghazi, Libya, and a string of demonstrations on other U.S. embassies in the Middle East and North Africa.
On Thursday, measures to beef up security at U.S. embassies were passed out of the Senate Foreign Relations Committee. The bill is in response to the Sept. 11, 2012 attack on the diplomatic post in Benghazi, Libya, where Ambassador Chris Stevens and three other Americans were killed.
The Senate bill creates a training center for diplomatic security personnel.
Separately, the House Foreign Affairs Committee authorized full security funding for diplomatic missions -- despite recommending a nine percent cut overall for State Department operations.
The House and Senate have already approved spending bills that cover embassy security. But their budgets differ markedly in other areas.
Fox News' Justin Fishel and The Associated Press contributed to this report.