Al Qaeda was in the final stages of planning an unspecified attack in Yemen, according to a CNN report that seems to explain the widespread, planned closures of U.S. embassies across the Middle East on Sunday

CNN reports: 

A senior Yemeni national security official told CNN that the government was "on high alert against possible attacks in the days to come. The threat appears much worse than it has in a long time," the Yemeni official said. According to three sources, the United States has information that al Qaeda in Yemen was in the final stages of planning for an unspecified attack.

The report would also explain the timing of the closures, along with why the State Department opted to shut down so many embassies (emphasis ours): 

One of the sources said the preparations appeared to have increased in recent days with the approaching end of the Muslim holy month of Ramadan, while a U.S. official noted it was unclear whether the plot would be directed at a target inside Yemen or elsewhere.

Rep Peter King, the Republican Chairman of the Subcommittee on Counterterrorism and Intelligence, weighed in on the alleged plot on Friday, calling the threat "the most specific" he's seen in several years of getting intelligence briefings. “You see unprecedented actions, 21 embassies being closed, the global travel advisory being given. This is being taken very, very seriously,” he told CNN (via Politico). 

On Friday, the U.K. announced that they would close their Yemen embassy for at least two days starting on Sunday. The Foreign Office also re-upped their travel warning for the country. Their existing warning reads "If you travel to Yemen against our advice, you should regularly reassess your security and plan any movements around the country carefully." The warning, updated Friday, adds that the U.K. "strongly urge[s] British nationals to leave now." 

The U.S. State Department has also issued a travel warning for Americans travelling worldwide, focusing on "the continued potential for terrorist attacks" in the Middle East in August. "current information suggests that al Qaeda and affiliated organizations continue to plan terrorist attacks," the warning continued, with little information beyond that.