The CIA says that a new audio recording, attributed to Al Qaeda's No. 2 man, is probably authentic.

In the audio message, first aired on Sunday, the voice purportedly of Ayman al-Zawahri (search) accused the United States of trying to abolish Islam.

The audio message, aired in excerpts on the Al-Jazeera and Al-Arabiya television networks, referred to recent events, including a visit by Israeli Prime Minister Ariel Sharon (search) to India in early September and the Sept. 6 resignation of Palestinian Prime Minister Mahmoud Abbas (search).

Al-Zawahri, an Egyptian, is bin Laden's top surviving deputy and is thought to be in the remote region along the border of Afghanistan and Pakistan.

He said that what the West calls terrorism is jihad. He urged Muslims to "resist this Jewish crusade."

"I thus call for jihad (holy war) against this campaign that seeks to end Islam as a doctrine and law and turn us into a herd that follows the lords of Washington, Tel Aviv and London," the speaker said.

U.S. intelligence officials are unsure why al-Zawahri, instead of Usama bin Laden, has done most of the talking for Al Qaeda lately. Some speculate bin Laden may be avoiding recording new messages as a security precaution; some experts have suggested its a sign that bin Laden is somehow incapacitated or out of touch.