CAIRO, Egypt – Osama bin Laden’s chief deputy claimed America was on the brink of defeat in Iraq and Afghanistan in a videotape broadcast yesterday that appeared to be a rallying call for Al Qaeda ahead of the anniversary of the September 11 attacks.

“The defeat of America in Iraq and Afghanistan has become a matter of time, with God’s help,” Ayman al-Zawahri said on the tape, broadcast by the pan-Arab television station Al Jazeera. “The Americans in both countries are between two fires, if they continue they bleed to death and if they withdraw they lose everything.”

A bearded Mr. al-Zawahri, wearing eyeglasses, a white turban and a black vest over a white shirt, spoke looking into the camera. An assault weapon was leaning on the wall behind him.

American forces face fierce resistance in parts of Afghanistan and across Iraq, but military commanders insist they maintain the upper hand against insurgents in both countries.

Al Qaeda has issued a bin Laden audio tape in the two previous years on September 10, so yesterday’s video fits a pattern leading up to the attack anniversary, an American intelligence official said. Intelligence officials were working to confirm the speaker was Mr. al-Zawahri.

It it would be the first time since December of 2001 that Mr. bin Laden’s No. 2 has appeared in a video in which he is speaking and delivering a message, the official said, although he was purported to have made a statement in an audiotape on June 11.

Mr. al-Zawahri also was shown speaking on a videotape on April 15,2002,but Defense Secretary Rumsfeld said at the time that the material appeared to be outdated. Experts were investigating what message the video released yesterday might be seeking to convey and whether the videotape is an older audiotape, now joined with its images.

American officials have noted that some tape releases have preceded terrorist attacks. In April of 2003, a taped voice thought to be Mr. bin Laden’s exhorted Muslims to rise up against Saudi Arabia and called for suicide attacks against American and British interests. Suicide bombers struck Western housing compounds in the Saudi capital on May 12, killing 26 people.

Al Jazeera spokesman Jihad Ballout said his station received the al-Zawahri tape yesterday, but he refused to say how it was obtained. The station will broadcast less than two minutes of a 12-minute recording, “taking out of it what we deemed newsworthy,” Mr. Ballout said.

A Pakistani army spokesman, General Shaukat Sultan, said the tape was likely aimed at “boosting the morale of the terrorists who have suffered heavy casualties.” In a videotape released on September 10, 2003, Messrs. bin Laden and al-Zawahri were shown walking through rocky terrain. Two audiotape messages accompanied that video, including one in which Mr. bin Laden praised the “great damage to the enemy” done on September 11.

In this year’s tape, Mr. al-Zawahri makes a rare appearance without Mr. bin Laden, proclaiming that the era of security for Americans is over and they will never enjoy it again unless their government stops what he described as crimes against Muslims in Iraq, Afghanistan, and Palestine. He also warned of plans to tear apart the Arab and Islamic worlds, saying that includes the Arabian Peninsula, Egypt, and Sudan.