Citing a "credible and serious" terror threat, the State Department has ordered several US embassies in the Middle East to shut down on Sunday. No word on how long they will remain closed.

CNN:

A U.S. official not authorized to speak publicly on the matter called the threat "credible and serious."

It was "directed at American targets overseas," but may not be confined to main diplomatic facilities, the official said.

In addition to Egypt and Israel, the State Department action includes diplomatic facilities in Saudi Arabia, Libya, Iraq and Kuwait, according to the agency and Twitter postings.

A senior State Department official said the agency has told those embassies that normally would be beginning the work week on Sunday to close, but additional days could be added.

Diplomatic facilities in the region are for the most part closed or operate with minimal staff on Fridays and Saturdays.

Separately, another U.S. official told CNN that the Obama administration is monitoring threats against the embassy in Sanaa, Yemen.

The official did not say whether the embassy would close.

President Barack Obama met with Yemen President Abdo Rabu Mansour Hadi at the White House on Thursday. Yemen has been cracking down on al Qaeda.

A U.S. official earlier told CNN the embassy closures were because of "more than the usual chatter" about a potential terrorist threat, which was not specific about time and location.

Officials said the time frame comes with the approaching end of Ramadan and the one-year anniversary of the terror attack on the U.S. diplomatic compound in Benghazi, Libya, that killed four Americans, including Ambassador Christopher Stevens.

State Department spokeswoman Marie Harf said the agency was taking the steps at diplomatic sites out of an abundance of caution.

The U.S. Embassy in Cairo noted on its website media reports of possible marches or demonstrations on Friday and possibly throughout the weekend.

I think it is significant that what these closings say is that we don't trust the host governments to protect our people. We can debate security at our embassies, but the bottom line is that overall security is in the hands of the host government. We obviously feel that many of them are incapable - or unwilling - to protect our diplomats.

It's a legitimate question to ask why they didn't take this step last September 11, given the concerns of Ambassador Stevens and others in the State Department. If this is the way we have to learn our lessons about terrorism, we will no doubt experience more attacks