The Nigerian man suspected of trying to blow up a Detroit-bound airliner on Christmas Day told investigators after his arrest that close to 20 other young Muslim men were being trained in Yemen to blow up airliners, CBS News reports.
Umar Farouk Abdulmutallab's claim that others were being prepared to use the same technique on jets reportedly was confirmed by British intelligence.
Sources told CBS that his statement was behind the U.S.-issued directive announcing "enhanced screening" for "every individual" on U.S.-bound flights from 14 countries.
Abdulmutallab pleaded not guilty Friday to charges that he tried to blow up the Northwest Airlines jet.
He said little during a federal court hearing that lasted less than five minutes. The 23-year-old, who wore a white T-shirt, tennis shoes and light olive pants, said "yes" in English when asked if understood the charges against him.
Authorities say Abdulmutallab was traveling from Amsterdam when he tried to destroy the plane carrying nearly 300 people by injecting chemicals into a package of explosives concealed in his underwear. The failed attack caused popping sounds and flames that passengers and crew rushed to extinguish.
A grand jury indicted Abdulmutallab on six charges earlier this week. The most severe carries up to life in prison — the attempted use of a weapon of mass destruction.
During Friday's hearing, Abdulmutallab stood at the podium along with Assistant U.S. Attorney Jonathan Tukel and defense attorney Miriam Siefer and answered a few questions from Magistrate Judge Mark A. Randon.
When the judge asked if he had taken any drugs or alcohol in past 24 hours, he answered, "some pain pills." Siefer then said he was competent to understand the proceedings. Abdulmutallab, who is being held at a federal prison in Milan, Mich., had been treated at a hospital for burns after the attack.
His attorneys then waived the reading of the indictment, and the judge entered not guilty plea on his behalf.
The Associated Press contributed to this report.