Usama bin Laden's call for a rebellion in Pakistan is a "serious" threat, U.S. officials said Thursday, noting that President Pervez Musharraf already is facing difficulties at home.
In a new audio message posted by an Islamic Web site, the Al Qaeda chief said Musharraf's military siege of a militant mosque stronghold earlier this year made him an infidel.
The storming of the Red Mosque in Islamabad in July "demonstrated Musharraf's insistence on continuing his loyalty, submissiveness and aid to America against the Muslims ... and makes armed rebellion against him and removing him obligatory," bin Laden said in the tape.
"So when the capability is there, it is obligatory to rebel against the apostate ruler, as is the case now," he said, according to a transcript of the tape released by Laura Mansfield, an American terror expert who monitors militant message traffic.
Bin Laden's voice was heard over video showing previously released footage of the terror leader. U.S. officials, who spoke on the condition of anonymity said the audio was being analyzed but noted there had never been a "fake" bin Laden or Zawahiri tape.
The message, titled "Come to Jihad," was the third from bin Laden this month in a flurry of videos and audiotapes marking the sixth anniversary of the Sept. 11 attacks in the United States.
Maj. Gen. Waheed Arshad, a Pakistani army spokesman, said the army will continue its fight against terrorism, regardless of any threats.
"We have the aim and objective, as our national duty, to eliminate terrorists and eradicate extremism. The Pakistan army will continue to carry out its role against terrorists wherever they are found, whether in the tribal areas (of northwest Pakistan) or elsewhere."
"Such threats issued through videos or in any other way cannot deter us from fulfilling our national duty," he said.
State Department spokesman Tom Casey said the message was "not surprising" since Pakistan is an ally to the U.S. in the fight against terrorism.
Earlier Thursday, Al Qaeda released an 80-minute documentary-style video that had a new speech from bin Laden's deputy, Ayman al-Zawahri, who boasted that the United States was being defeated in Afghanistan, Iraq and other fronts. Speakers in the video promised more fighting in Afghanistan, North Africa and Sudan's Darfur region.
The Pakistani military stormed the Red Mosque after it became a stronghold for Islamic militants and at least 102 people were killed in the fighting, including one of the militants' leaders, Abdul Rashid Ghazi. The siege was followed by a series of suicide bombings in retaliation.
In his message, bin Laden said Ghazi and his followers were killed for seeking the application of Sharia Islamic law, and he condemned Musharraf for allying himself with the U.S. in the fight against Al Qaeda.
He quoted fatwas, or religious edits, from hard-line Islamic scholars on the duty to overthrow infidel rulers.
"So Pervez, his ministers, his soldiers and those who help him are all accomplices in the spilling the blood of those of the Muslims who have been killed. He who helps him knowingly and willingly is an infidel like him," bin Laden said.
Al Qaeda leaders have railed against Musharraf and urged Pakistanis to rise up against him in past messages -- but the call from bin Laden now may be aimed at adding weight to the rallying cry. The Pakistani president has come under four assassination attempts since 2002.
Bin Laden and al-Zawahiri are thought to be hiding in the lawless Pakistan-Afghanistan border region, where many analysts believe they have rebuilt Al Qaeda's core leadership.
Thursday's other video underlined Al Qaeda's growing technical sophistication in its videos, interspersing al-Zawahiri's speech with scenes from the Sept. 11 attacks, interviews with experts and officials taken from Western and Arab broadcasters, and old footage and audio of bin Laden.
The tone was triumphal, with al-Zawahri calling for attacks on French and Spanish interests in North Africa and on U.N. and African peacekeepers expected to deploy in Darfur.
"What they claim to be the strongest power in the history of mankind is today being defeated in front of the Muslim vanguards of jihad six years after the two raids on New York and Washington," al-Zawahiri said.
The video included footage of Al Qaeda's leader in Afghanistan, Mustafa Abu al-Yazeed, meeting with a senior Taliban commander. In contrast to past videos showing Al Qaeda and Taliban fighters in rough desert terrain, Abu al-Yazeed and the commander were shown sitting in a field surrounded by trees as a jihad anthem played, extolling the virgins that will meet martyrs in paradise.
Abu al-Yazeed said Al Qaeda's ties with the Taliban were strengthening. The Taliban commander, Dadullah Mansoor, vowed to "target the infidels in Afghanistan and outside Afghanistan" and to "focus our attacks, Allah willing, on the coalition forces in Afghanistan."
Another clip in the video showed Abu Musab Abdulwadood, the leader of Algeria's main Islamic insurgency movement, addressing bin Laden and vowing that "our swords are unsheathed."
Al-Zawahiri called on supporters in North Africa to "cleanse the Maghrib (western region) of Islam of the children of France and Spain. ... Stand with your sons the mujahedeen against the Crusaders and their children."
He denounced Sudanese President Omar al-Bashir for agreeing to an international peacekeeping force in Darfur, saying, "the free mujahid (holy warrior) sons of Sudan must arrange jihad against the forces invading Sudan in the same way their brothers arranged the jihadi resistance in Afghanistan, Iraq and Somalia."
The video also included old, but previously unreleased footage of bin Laden, according to IntelCenter, a U.S. counterterrorism group that monitors militant messages.
The images show bin Laden, with a beard streaked with gray and white cloth draped over his head, in front of a map showing the Middle East and South and Central Asia.
He condemns Arab Gulf governments that have allied themselves with the United States, saying they have "sold the Islamic nation, colluded with the enemies of Islam and backed the infidels."
The Associated Press contributed to this report.