In a direct challenge to President-elect Barack Obama, Osama bin Laden questions whether America "is capable to keep fighting us for more years" in a new audio message attributed to him Wednesday morning on an internet website.
A senior U.S. official told ABCNews.com, "There is no reason to doubt the authenticity of the tape."
It is the first time bin Laden has been heard from in seven months and puts to rest speculation he is dead. The al Qaeda leader's last audio message was posted on May 18, 2008.
"This is part of their ongoing propaganda effort to appear relevant by commenting on current events," the senior US official said in dismissing the significance of the new tape.
National Security Council spokesman Gordon Johndroe said the tape demonstrates bin Laden's isolation and "continued attempts to remain relevant at a time when Al Qaeda's ideology, mission, and agenda are being questioned and challenged throughout the world." He said it appeared to be a fundraising effort for al Qaeda's propaganda campaign.
Today's message begins with a call for a jihad against Israel because of its attacks on Gaza but concludes with a challenge to the U.S., and implicitly the incoming Obama administration.
"Now America is begging the world for money," bin Laden says, "and the USA will not be as powerful as it used to be."
"This rapid failing for America was one of the reasons that the Israelis started their attacks against Gaza and just to make use of what's left of the Bush term," he says.
Bin Laden makes reference to Vice-President elect Joseph Biden, quoting him as saying "the financial crisis is bigger than we expected" and the al Qaeda leader counsels patience in continuing to fight the U.S.
Bin Laden appears to be referring to comments Biden made to ABC News' George Stephanopolous in an Dec. 21 appearance on This Week.
"The economy is in much worse shape that we thought it was in," Biden said then.
"The majority of the U.S. people are happy to get rid of Bush, Bush left for his successor a heavy heritage, the hardest part of heritage is guerilla wars," bin Laden says.
During the campaign, Obama said the capture or death of bin Laden, and the defeat of al Qaeda, would be one of his administration's highest priorities.
Just yesterday, incoming Obama officials participated with their counterparts in the Bush administration in a table-top exercise to prepare for a possible terror attack during the Presidential transition.
U.S. officials say they are evaluating threat value of the new audio message, but no change to the threat level is anticipated. They said a conversation will be had given the upcoming inauguration.
Pierre Thomas contributed to this report.