Hundreds of people linked to al-Qaida, Hamas, Lashkar-e-Taiba and other terror groups have been kept off airplanes under the new rules. They include what U.S. officials described as a member of a terrorist organization who received weapons training, recruited others, fought against American troops and had a ticket to fly to the U.S. Another traveler prevented from boarding a U.S.-bound flight was a member of a terrorist organization whom intelligence officials believe had purchased equipment for terrorism.
A third case, in January, involved a Jordanian man booked from Amman, Jordan, to Chicago, who was considered a threat to national security, according to a law enforcement official. The State Department had already revoked his visa. He was on the terrorist watch list but not the no-fly list. He was not considered a threat to aviation.
After U.S. Customs and Border Protection officers performed the now-routine check, the man was kept off the flight. Before the change, he would have arrived in Chicago, where he would have likely been stopped at customs, questioned and sent home.
The law enforcement official and other U.S. officials insisted on anonymity to discuss sensitive security issues. They would not provide the names of the people suspected of terror ties or some key details about the cases for security reasons.
"We've gotten better with our techniques and applying them predeparture, ensuring we're looking at as broad a section of potential risk as possible," said Kevin McAleenan, deputy assistant commissioner of field operations at Customers and Border Protection.
CBP said the gap in U.S. security practices wasn't obvious until after the attempted Christmas attack. Officials were prepared to question the accused bomber when he landed in Detroit — but that turned out to be too late.