Continued from page 1

Just last winter, al Qaeda’s Yemen branch boasted that it had obtained a supply of chemicals used to make bombs. Chemicals can eliminate the need for electrical equipment to detonate explosives.

“Hence, no wearisome measures are taken anymore to attain the needed large amount of chemicals for explosives,” the group wrote in its online magazine, “Inspire.”

The CIA caught wind of the bomb plot last month, officials said, speaking on condition of anonymity to discuss intelligence matters.

The would-be bomber was supposed to buy a plane ticket to the United States and detonate the bomb inside the country, officials said.

Sen. Dianne Feinstein, D-Calif., who heads the Senate Intelligence Committee, told reporters Monday night that she had been briefed about an “undetectable” device that was going to be on a U.S.-bound airliner.

Before the bomber could choose his target or buy his ticket, however, the CIA moved in and seized the bomb.

The fate of the would-be bomber remains unclear. Rep. Peter King, R-N.Y., chairman of the House Homeland Security Committee, told CNN on Tuesday that White House officials told him, “He is no longer of concern,” a point Brennan echoed on a round of appearances Tuesday on television news shows.

“We’re confident that this device and any individual that might have been designed to use it are no longer a threat to the American people,” Brennan said.

The plot was a reminder of the ambitions of al Qaeda in Yemen, the most active and dangerous branch of the terrorist group. While al Qaeda’s core in Pakistan has been weakened over the past decade, instability in Yemen has allowed an offshoot group to thrive and set up training camps there. In some parts of the country, al Qaeda is even the de facto government.

Though analysis of the device is incomplete, U.S. security officials said they remained confident in the security systems that are in place.

“These layers include threat and vulnerability analysis, prescreening and screening of passengers, using the best available technology, random searches at airports, federal air marshal coverage and additional security measures both seen and unseen,” Homeland Security spokesman Matthew Chandler said.

“The device did not appear to pose a threat to the public air service, but the plot itself indicates that these terrorists keep trying to devise more and more perverse and terrible ways to kill innocent people,” Secretary of State Hillary Rodham Clinton said during a news conference in New Delhi with Indian External Affairs Minister S.M. Krishna.

It’s not clear who built the bomb, but because of its sophistication and its similarity to the Christmas Day bomb, authorities suspect it was the work of master bomb maker Ibrahim Hassan al-Asiri or one of his students. Al-Asiri constructed the first underwear bomb and two others that al Qaeda built into printer cartridges and shipped to the U.S. on cargo planes in 2010.

Both of those bombs used a powerful industrial explosive. Both were nearly successful.

But the group has also suffered significant setbacks as the CIA and the U.S. military focus more on Yemen. On Sunday, Fahd al-Quso, a senior al Qaeda leader, was killed by a missile as he stepped out of his vehicle along with another operative in the southern Shabwa province of Yemen.

Story Continues →