"America, which cooperated with [President] Bashar Assad during his whole regime, claims today that it stands with you when it saw him floored by the earthquake caused by your fury," Ayman al-Zawahiri said in a video titled "Glory of the East Starts in Damascus" posted on extremist Web sites.
It was his first video message since al-Qaida announced June 16 it named him its leader after Osama bin Laden was killed May 2 in a U.S. commando raid in Pakistan.
Washington may appear to support anti-Assad activists, whose uprising began March 15, but the United States actually wants to replace his rule "with another regime that squanders your revolution and jihad [holy war] in a new regime that follows America, takes care of Israel's interests and grants the Ummah [Muslim community or nation] some freedoms," Zawahiri said in remarks translated by the Search for International Terrorist Entities Intelligence Group and cited in The Washington Post.
SITE of Bethesda, Md., tracks terrorist organizations' online activities.
Zawahiri is believed to speak Arabic, French and English.
The U.S. State Department offered a $25 million reward for information leading to his capture after the Sept. 11, 2001, terrorist attacks.
"Tell both America and [U.S. President Barack] Obama ... our powerful uprising will not stop until we raise the victorious banner of jihad ... over Jerusalem," Zawahiri said in the video showing him dressed in a white robe, turban and large glasses and seated next to an assault rifle.
Zawahiri, 60, blamed the U.S. war against al-Qaida for preventing him from joining the activists, whom he called "mujahedin," or "holy warriors," in their anti-Assad uprising.
"If it were not for that, my brothers and I would have been amongst you and with you, defending you with our lives," he said in the video, which contained the word Rajab, the seventh Islamic month, which began June 3 and ended July 1.
Rajab is regarded as one of the four sacred months in Islam in which battles are prohibited.
Zawahiri accused Assad of being both a corrupt tyrant and "America's partner in the war on Islam."