An intercepted message among senior al-Qaeda operatives in the last several days raised alarm bells that led to the closing of US embassies and consulates Sunday across the Middle East and North Africa, the (CNN) has learned. Several US officials also emphasized they have been watching growing threats emerging from Yemen for weeks. Those threats, combined with the coming end of the month of Ramadan, plus the concern over several major prison breaks in the region, all contributed to the US decision to shut down diplomatic installations. Officials shuttered 22 US embassies and consulates for the day on Sunday amid fears of an al-Qaeda attack. On Sunday afternoon, the State Department said it had extended embassy and consulate closures in 15 of the locations until Friday and added four other posts to the list. \"This is not an indication of a new threat stream,\" the State Department said, \"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 widespread closure of diplomatic posts is an unprecedented move. \"We\'re doing what is necessary to protect our people,\" Rep. Adam Schiff, a Democrat on the House Intelligence Committee, told CNN\'s State of the Union on Sunday. CNN national security analyst Fran Fragos Townsend said there could be a strategic reason for shutting down the diplomatic offices. \"Once you take targets away, it buys you additional time to try and disrupt, to identify the cell, the operators in country and the region, and work with your partners in the region to try and, you know, get them in custody or disrupt the plot,\" she said. \"So, some of this operationally is about buying time.\" Of particular concern is Yemen, where the government is \"on high alert against possible attacks in the days to come,\" said a senior U.S. security official. Over the weekend, the security around the U.S. Embassy in Yemen was even tighter than last year, when protesters raided it. At least 12 tanks were stationed within 500 meters of the building. Britain, France and Germany also closed their embassies in the Yemeni capital, Sanaa, on Sunday and Monday for security reasons. No other embassies are affected, they said.