The CIA has thwarted an ambitious plot by al Qaida's affiliate in Yemen to destroy a US-bound airliner using a bomb with a sophisticated new design around the one-year anniversary of the killing of Osama bin Laden.
The plot involved an upgrade of the underwear bomb that failed to detonate aboard a jet over Detroit, Michigan, on Christmas Day 2009.
The new bomb also was designed to be used in a passenger's underwear, but this time al Qaida developed a more refined detonation system, US officials said.
The FBI is examining the latest bomb to see whether it could have passed through airport security and brought down a plane, officials said.
They said the device did not contain metal, meaning it probably could have passed through an airport metal detector. But it was not clear whether new body scanners used in many airports would have detected it.
There were no immediate plans to change security procedures at US airports.
The would-be suicide bomber, based in Yemen, had not yet picked a target or bought a plane ticket when the CIA stepped in and seized the bomb, officials said. It was not immediately clear what happened to the alleged bomber.
White House spokeswoman Caitlin Hayden said President Barack Obama learned about the plot in April and was assured the device posed no threat to the public. "The President thanks all intelligence and counter-terrorism professionals involved for their outstanding work and for serving with the extraordinary skill and commitment that their enormous responsibilities demand," she said.
The operation unfolded even as the White House and Department of Homeland Security assured the American public that they knew of no al Qaida plots against the US around the anniversary of bin Laden's death. The operation was carried out over the past few weeks, officials said.
The White House did not explain those statements.