Hawaii - A wing of al Qaeda claimed responsibility on Monday for a failed Christmas Day attack on a U.S.-bound passenger plane and President Barack Obama vowed to bring every element of U.S. power against those who threaten Americans' safety.
In a statement posted on Islamist websites, the group Al Qaeda in the Arabian Peninsula said the attempt was to avenge U.S. attacks on them in Yemen.
It said it had provided the Nigerian suspect in the failed airliner bombing with a technically advanced device but that it did not detonate because of a technical fault.
Umar Farouk Abdulmutallab, 23, is charged with smuggling explosives on board and attempting to blow up a Northwest Airlines flight as it approached Detroit from Amsterdam on December 25 with almost 300 people on board.
Speaking during a vacation in Hawaii, Obama said: We will not rest until we find all who were involved and hold them accountable.
We will continue to use every element of our national power to disrupt, to dismantle and defeat the violent extremists who threaten us, whether they are from Afghanistan or Pakistan, Yemen or Somalia, or anywhere where they are plotting attacks against the U.S. homeland.
Abdulmutallab has told U.S. investigators that al Qaeda operatives in Yemen supplied him with an explosive device and trained him on how to detonate it, officials said over the weekend.
The incident has put a spotlight on the growing prominence of al Qaeda in Yemen, and on the expanding role of the U.S. military and spy agencies in fighting the group.
Obama is under pressure from opposition Republicans who have been critical of his response to the Christmas Day scare and have questioned whether his administration is doing enough to contain security threats.
His administration admitted on Monday that the incident represented a failure of air security.
Asked on NBC's Today Show on Monday if the security system failed miserably, U.S. Homeland Security Secretary Janet Napolitano replied: It did.
Abdulmutallab, who was travelling with a valid U.S. visa although he was on a broad U.S. list of possible security threats, was overpowered by passengers and crew on the Northwest Airlines flight 253 after setting alight an explosive device attached to his body.
He was treated for burns and is in federal prison awaiting trial in the incident.
In Nigeria, Abdulmutallab's family said they had reported his disappearance to security agencies months ago after becoming concerned about his increasing militancy.
Airline stocks fell on Monday as the United States tightened airline security after the incident. AMR Corp, the parent of American Airlines, lost 5.9 percent to $7.66.
The U.S. Transportation Security Administration did not give details of its new security measures. But air travellers described new restrictions on flights headed for the United States, including additional preflight screening, and -- an hour before landing -- a ban on movement around the cabin and on having items such as blankets on passengers' laps.
(Additional reporting by Firouz Sedarat in Dubai, Debbie Charles, Adam Entous and Patricia Zengerle in Washington and Bernie Woodall in Detroit; Chuck Mikolajczak in New York and Camillus Eboh in Abuja; Writing by Jackie Frank, editing by Frances Kerry)