A purported audio tape of Osama bin Laden aired on Al-Jazeera television claimed responsibility for the attempted bombing of a US-bound plane last month.
In the tape, broadcast today, the al-Qaeda leader vowed to continue attacks on the United States.
"The message sent to you with the attempt by the hero Nigerian Umar Farouk Abdulmutallab is a confirmation of our previous message conveyed by the heroes of September 11th," bin Laden said in the minute-long message.
"If it was possible to carry our messages to you by words we wouldn't have carried them to you by planes," bin Laden added in a message he said was directed "from Osama to Obama".
The Yemen-based regional wing of al-Qaeda has said it was behind the December 25th attempt to blow up the plane as it approached Detroit on a flight from Amsterdam. The botched attack and subsequent threats in Yemen prompted Sanaa to declare an open war on the global militant group within its territory.
Yemen has launched a series of air strikes targeting al-Qaeda leaders since then and has declared that some top leaders including Qasim al-Raymi and Ayed al-Shabwani have been killed. Al-Qaeda denies this.
Defence and counterterrorism officials say Washington has been quietly supplying military equipment, intelligence and training to Yemen to destroy suspected al-Qaeda hide-outs.
On the tape, bin Laden cited Washington's support for Israel as the motivator for more attacks on the United States, and vowed not to stop so long as Palestinians cannot live in peace.
"Our attacks against you will continue as long as US support for Israel continues," he said. "It is not fair that Americans should live in peace as long as our brothers in Gaza live in the worst conditions."
There was no way to confirm the voice was actually that of bin Laden, but it resembled previous recordings attributed to him.
A top White House official said today he could not confirm the authenticity of the tape. "I can't confirm [the claim of responsibility for the attack] nor can we confirm the authenticity of the tape, but assuming that it is him, his message contains the same hollow justifications for the mass slaughter of innocents that we've heard before," David Axelrod said on CNN's State of the Union programme.
"The irony is that in the name of Islam he's killed more Muslims than people from any other religion,” Mr Axelrod added. “He's a murderer and we're going to continue to be on the offense against bin Laden, against al-Qaeda, to protect the American people."
Israeli Foreign Ministry spokesman Andy David dismissed the message and its attempt to link Israel with attacks on the US. “This is nothing new. He has said this before,” he said. “Terrorists always look for absurd excuses for their despicable deeds.”
One analyst said the message suggests the al-Qaeda leader wants to appear in direct command of the terrorist group’s many affiliates around the world at a time when many intelligence experts have suggested he is mostly a figurehead.
Rohan Gunaratna, author of Inside Al Qaeda: Global Network of Terror, said bin Laden was exploiting the attack for his own benefit. "Bin Laden still wants to claim leadership for the global jihad movement."
Of all the various offshoots and branches of al-Qaida around the world, Mr Gunaratna said the group in Yemen is one of the closest to bin Laden since it is made up of bodyguards and associates of the organisation’s top ideologues. Yemen is bin Laden’s ancestral homeland. Two of the group’s top members were former detainees released in November 2007 from Guantanamo Bay.
Analysts have long debated how much control bin Laden, who is believed to be somewhere in Afghanistan-Pakistan border region, really has over the various organisations using his group’s name.
In the past year, bin Laden’s messages have concentrated heavily on the situation of the Palestinians in attempt to rally support from Muslims around the world.
Some analysts say bin Laden is focusing on the close US-Israeli relationship because he is worried about Mr Obama’s popularity across the Middle East with his promises to withdraw from Iraq and because his father was a Muslim from the African nation of Kenya.
“The Palestinian conflict was never part of the al-Qaeda original mandate, but Osama is clearly exploiting it,” Mr Gunaratna said.
Agencies