HONOLULU — President Barack Obama emerged from Hawaiian seclusion on Monday to reassure the American public and quell gathering criticism as a branch of al-Qaida claimed responsibility for the thwarted attack on Christmas Day on an American passenger jet.
Obama vowed to track down "all who were involved" in helping a Nigerian man try to set off explosives aboard a Northwest Airlines flight as the plane approached Detroit, acknowledging the conclusion that the act was not that of a lone wolf but of a trained al-Qaida operative. With more signs pointing to Yemen as the origin of the attack, the White House was weighing how to respond.
The president broke his silence as debate about the episode turned increasingly political. An assertion over the weekend by Janet Napolitano, the homeland security secretary, that "the system worked" drew strong criticism and forced her to recalibrate it on Monday.
Napolitano said that her remark had been taken out of context and that the attempted attack in fact represented a failure of the security system. "Our system did not work in this instance," she said. "No one is happy or satisfied with that."
On the international front, a group called al-Qaida in the Arabian Peninsula, which operates in Yemen and was the target of a recent airstrike facilitated by the United States, asserted that it had sponsored the attempted attack in retaliation.
U.S. government officials said they considered the statement, which was posted on a jihadist Web site, credible. The Yemeni government said the suspect in the failed bombing, Umar Farouk Abdulmutallab, 23, had spent four months in the country before leaving earlier in December.
The statement by al-Qaida on the Arabian Peninsula, accompanied by a photograph of Abdulmutallab, called him a hero who had "penetrated all modern and sophisticated technology and devices and security barriers in airports of the world" and "reached his target."
The statement said "mujahedeen brothers in the manufacturing department" had supplied the explosives and while a "technical error" led to an "incomplete detonation," the group vowed to "continue on the same path."
ABC News, citing unnamed American officials and Department of Defense documents, reported that two of the four leaders allegedly behind the plot were released by the United States from the Guantanamo prison. It said Guantanamo prisoner No. 333, Muhamad Attik al-Harbi, and prisoner No. 372, Said Ali Shari, were sent to Saudi Arabia on Nov. 9, 2007. Al-Harbi has since changed his name to Muhamad al-Awfi.
The claim of responsibility by the Yemeni branch of al-Qaida could force a shift in the administration's approach to counterterrorism in that nation. Until now, U.S. authorities considered it important to give Yemen credit for recent strikes against al-Qaida training camps and leaders, playing down the U.S. role in providing intelligence and equipment.
But a direct attempt to launch an attack on U.S. soil raises the question of whether the United States would have to take broader and more clearly visible retaliatory military action.
Obama, making his first public comments since the episode, said he had ordered his national security team "to keep up the pressure" on terrorists and vowed to "use every element of our national power to disrupt, 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 on the U.S. homeland."
Although he had been out of sight for three days, he assured Americans he was on top of the situation.
"We will not rest until we find all who were involved and hold them accountable," Obama said. "This was a serious reminder of the dangers that we face and the nature of those who threaten our homeland."
Rep. Peter King of New York, the ranking Republican on the House Homeland Security Committee, criticized Obama's silence Monday before the president's statement. "We're now, what, 72 hours into this and the president's not spoken, the vice president's not spoken, the attorney general's not spoken and Janet Napolitano has now told two different stories in two days," he said on Fox News. "First, she said everything worked; now she said it didn't."