Key Democratic and Republican members of Congress said Sunday that the terrorism threat reportedly triggered by an intercepted message between senior al Qaeda operatives is the most serious threat in years, with some warning that the threat is an indication the terrorist group responsible for the 9/11 attacks still poses a significant danger to the U.S., the Washington Times reports. The threat forced the closings of more than 20 U.S. embassies and consulates this weekend. A travel alert was issued for Americans planning to travel overseas, particularly in the Middle East, and will remain in effect for the rest of August. The closures of the embassies and consulates and the travel alert were triggered by an intercepted message between senior al Qaeda operatives, CNN reported Sunday. The State Department announced Sunday afternoon that 19 diplomatic posts will remain shuttered through Saturday, underscoring the level of concern by U.S. security officials about the potential danger. Department spokeswoman Jen Psaki said the extension was ordered in part because of the looming celebrations marking the end of the Ramadan period of fasting for Muslims and in part out of "an abundance of caution. ... This is not an indication of a new threat stream, 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 U.S. posts that will remain closed for the week include embassies and consulates in Jordan, Egypt, Saudi Arabia, Kuwait, Yemen, Libya and Somalia.