Al-Qaeda's leader said he is praying that the Arab Spring will be followed by a "gloomy, bitter-cold American winter," in a video monitoring group SITE Intelligence said was released to mark the anniversary of 9/11.
"After the Arab people's revolutions we ask Allah that the US has a gloomy, bitter-cold winter that it will not escape," said Ayman al-Zawahiri, Al-Qaeda's new chief, in the 62-minute video entitled "The Dawn of Imminent Victory."
The video also includes a speech by Al-Qaeda's leader Osama bin Laden, who was killed in Pakistan on May 2 by US commandos.
US monitoring service SITE said the footage of bin Laden appears to be the same material found in the US raid on his Pakistan hideout in May, which Washington released but without its soundtrack.
Bin Laden, who was killed by US Navy SEALs in the covert operation, warned Americans against "falling as slaves" to the control of major corporations and "Jewish money capital", SITE said
He recommended that Americans read the book "Obama's War" by Bob Woodward which details wrangles over US military decision-making, and told them that US President Barack Obama's campaign slogan "Yes, we can" is untrue.
Zawahiri, who is now Washington's most wanted man, in the video makes a long speech about events in the past year, including the revolutions in the Arab world and the death of bin Laden whom he replaced after a long period as Al-Qaeda's number two.
"Zawahiri... declared that contrary to what is reported in the media, Al-Qaeda supports the revolutions and hopes it will establish true Islam and sharia-based governance," SITE said.
"The popular revolutions, he stated, are a form of defeat for the United States, just as the 9/11 attacks and its alleged lack of success in Afghanistan and Iraq were also defeats."
Al-Qaeda has been absent from the popular protests that have swept the Arab world this year, leading to the fall of leaders in Egypt, Libya and Tunisia and provoking major unrest elsewhere.
Analysts argue that the phenomenon has left the global terror outfit weakened and increasingly irrelevant.
Zawahiri also advised the Palestinian Authority against efforts to seek statehood status at the United Nations later this month, saying that such a move would amount to "losing even more of Palestine and recognising" the Israeli state.
He lauded his predecessor bin Laden as a fighter who had taken on the Russians in Afghanistan as well as the Americans, and whom he said had sacrificed everything for his campaign.
"America is denying the fact that it is not facing individuals or groups but the whole ummah (Muslim community) of Islam. After the martyrdom of Sheikh Osama, the Islamic face of the revolutions was shown," he said.
"America's arrogant nature will push it to deny the facts that it is facing a rising ummah and that it may be a cause of defeat and its fall, with permission from Allah."
Zawahiri was only shown in a still picture in the video, which was released by Al-Qaeda's media arm, as-Sahab, and posted on jihadist websites Monday.
Like his slain Saudi-born co-conspirator, Zawahiri has been in hiding since the United States declared its war on terrorism after the September 11, 2001 attacks.
The US on Sunday marked the 10th anniversary of the 9/11 strikes in emotional ceremonies held under tight security after federal authorities warned of a new terrorism scare.