All airlines flying to the United States or within the country were told Thursday to prepare for even tighter security because of the al-Qaida threat from Yemen, a law enforcement official said.
The U.S. increased the number of air marshals on international flights and pressed for more random screening at airports as intelligence officials warned that al-Qaida's branch in Yemen was continuing to plot attacks on the United States.
A U.S. counterterrorism official said American intelligence agencies were intensely examining all information about threats from the Yemen-based al-Qaida in the Arab Peninsula, including potential plots and specific individuals. Counterterrorism agencies have serious concerns about al-Qaida plots emanating from Yemen, the official said.
The officials did not pinpoint any specific evidence of new plots since the Christmas Day bombing attempt by a Nigerian national on a Detroit-bound flight. Both spoke on condition of anonymity because they were not authorized to discuss intelligence publicly.
Homeland Security Secretary Janet Napolitano said in a statement that travelers should allow for extra time, especially if flying into the U.S. from overseas, as officials stepped up security. "We are facing a determined enemy and we appreciate the patience of all Americans and visitors to our country, and the cooperation of our international partners as well as a committed airline industry," she said.
President Barack Obama was briefed Thursday by his national security team on progress against al-Qaida and its affiliates.
Al-Qaida's Yemeni offshoot has long aimed at U.S. targets. Yemeni terrorists almost sunk the USS Cole in 2000 with an explosion that killed 17 sailors. The U.S. Embassy there has closed several times over past threats.
Hundreds of names have been added to the terrorist watch list since Dec. 25, when a 23-year-old Nigerian man boarded a flight without a coat or checked bag from Amsterdam to Detroit. Bombing suspect Umar Farouk Abdulmutallab, who is alleged to have hidden an explosive in his underwear, was not on a watch list that would have called for extra screening before he boarded the U.S.-bound plane.
The administration has already added hundreds of air marshals to the existing force of more than 4,000. Napolitano said the air marshals would be assigned to flights on certain routes. There were no air marshals on Northwest Flight 253 on Christmas or on the same flight the following day.
The additional security measures Napolitano described Thursday are similar to what the administration asked of airlines since Christmas. Security directives for international travel are sent to airlines because the U.S. does not have the authority to regulate how foreign airports secure commercial air travel.
Spokespersons for several major U.S. airlines, including Delta, AirTran, US Airways and American, said there was nothing new on the security front that they could share publicly.
On its Web site, Delta was advising passengers to arrive for international flights at least three hours before departure. American was advising passengers to get to airports two to three hours early for international flights, depending on origin and destination.
U.S. airlines have not handled security screening at domestic airports since the aftermath of the Sept. 11 attacks, when the TSA was created to take over that task. At some airports overseas, however, airlines have been known to hire private security firms to help guard passengers, cargo and aircraft. That has been the case at times at Jomo Kenyatta International Airport in Kenya.
Associated Press writer Harry Weber contributed to this report from Atlanta.
© Copyright 2015 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.