The change is due to U.S. intelligence officials being concerned that al-Qaida is trying to develop a new and improved bomb that could sneak through airport security.
There is no proof that such a bomb has been built or that there's even a specific threat to the U.S., but the Obama administration on Wednesday called for security measures to be tightened at foreign airports that have direct flights to the U.S.
American intelligence has picked up indications that al-Qaida bomb makers from Yemen have traveled to Syria to link up with more terrorists there. He increased security has apparently been in the works for a few months.
U.S. counterterrorism officials say the call for increased security was not connected to the situation in Iraq, but out of an "abundance of caution," a U.S. official said.
The State Department has instructed embassy employees in Algeria to avoid hotels owned or operated by the U.S. through July 4 and the Algerian Independence Day on July 5.
"As of June 2014 an unspecified terrorist group may have been considering attacks in Algiers, possibly in the vicinity of a U.S.-branded hotel," according to the message from the U.S. Embassy in Algeria.
It’s not clear which airports are affected, but there are more than 250 foreign airports that fly directly to the U.S.