Osama bin Laden injected himself into the final days of the U.S. presidential campaign, warning that American voters will be held accountable for electing any president who seeks to destroy al Qaeda and persecutes Muslims.

"Your security is not in the hands of Kerry or Bush or al Qaeda," bin Laden, looking thinner but healthier than in previous tapes and speaking in a calm voice, said on a videotape broadcast yesterday. "Your security is in your own hands."

Bin Laden, in his first videotaped address in three years, displayed a fluency with American culture, mentioning "Manhattan," the USA Patriot Act and the 2000 election controversy in Florida. He made no explicit threat and did not issue a call to arms, as he has done since the Sept. 11, 2001, attacks.

Although he directed statements to the American public, many intelligence and other counterterrorism experts concluded bin Laden's primary goal was to use the U.S. campaign season to enhance his public profile rather than to sway the election.

"The tape is more about his own audience, about getting himself reelected as the head of the movement, than anything else," said Winston P. Wiley, former CIA deputy director of intelligence.

But the al Qaeda leader's appearance so close to Election Day prompted President Bush and Sen. John F. Kerry to interrupt campaigning to react. It also reignited the speculation over whether the world's most wanted terrorist favors one candidate.

Inside the CIA, one senior U.S. counterterrorism official said, "I've heard it argued either way . . . but listen to what he's saying. It doesn't matter who's president."

Bush supporters have generally said bin Laden would like Kerry elected, in the expectation of taking the heat off his network; Kerry supporters point to jihadist Web sites' recent statements that Bush's policies have so inflamed the Muslim world that he is their best recruiting draw. Each side disputes the other's interpretation.

"He's injecting himself into the campaign to show he's a world player," said Daniel Benjamin, a Clinton administration counterterrorism official who is now at the Center for Strategic and International Studies.

In the tape, bin Laden stands at a lectern in white and gold robes before a brown background. His environs are not visible, a sharp contrast to previous tapes that have shown him walking through rocky passes.

A CIA spokesman said analysts had a "high degree of confidence" in the tape's authenticity after performing voice and facial analysis. He said the tape, broadcast on the Arabic-language al-Jazeera network, displayed the date of Sunday, Oct. 24.

It was the first time since December 2001 that bin Laden both appeared and spoke on a videotape, he said. A videotape released in September 2003 showed him walking with senior al Qaeda leader Ayman Zawahiri, but there was no audio, and officials believe the video could have been old. An audiotape believed to have been recorded by bin Laden was released with it.

The spokesman noted that the address broadcast yesterday "lacked an explicit threat" and that the al Qaeda leader reiterated grievances against the United States and Israel.

In the speech, bin Laden attacked Bush, his father and their closeness to the Saudi monarchy.

Speaking of former president George H.W. Bush, bin Laden said, according to an Associated Press translation: "He wound up being impressed by the royal and military regimes and envied them for staying decades in their positions and embezzling the nation's money with no supervision."

"He passed on tyranny and oppression to his son, and they called it the Patriot Act, under the pretext of fighting terror. Bush the father did well in placing his sons as governors and did not forget to pass on the expertise in fraud from the leaders of the [Middle East] region to Florida to use it in critical moments."

Bin Laden said he was inspired to destroy the World Trade Center towers by Israel's 1982 attack on Lebanon, in which U.S. battleships aided with bombardments.

"As I watched the destroyed towers in Lebanon, I got the idea of punishing the oppressor the same way, by destroying towers in America so that it would taste some of what we have tasted and stop killing our children and our women," according to the SITE Institute's translation.

Bin Laden also ridiculed President Bush's initial reaction to the Sept. 11 attacks. He said Bush spent precious time "listening to a child discuss her goat," a reference to the minutes after Bush learned of the first attack and continued to sit in a Florida classroom listening to children read. "This had given us three times the time needed to carry out the operations." Bin Laden made several unusual references to "freedom." Juan Cole, a specialist in Middle Eastern affairs at the University of Michigan, said bin Laden is probably "annoyed that Bush has portrayed him as an enemy of freedom."

Cole said bin Laden may also be concerned about the recent election in Afghanistan and the backing the United States has gotten in Iraq for elections from Grand Ayatollah Ali Sistani, the Shiite leader, and he may be "feeling pressure from the success of the electoral process."

Bush has rarely spoken to reporters in his final campaign sprint, but he paused beside Air Force One in Toledo to address the tape.

"Americans will not be intimidated or influenced by an enemy of our country," he said. "I'm sure Senator Kerry agrees with this. I also want to say to the American people that we're at war with these terrorists and I am confident that we will prevail."

About the same time, Kerry told reporters in West Palm Beach, Fla.: "As Americans, we are absolutely united in our determination to hunt down and destroy Osama bin Laden and the terrorists. They are barbarians. And I will stop at absolutely nothing to hunt down, capture or kill the terrorists wherever they are, whatever it takes. Period."

Terrorism expert Rita Katz, founder of the SITE Institute, said she believes it is significant that the tape is being released during Ramadan, because al Qaeda publications have urged attacks during this time.

The SITE Institute reported on Oct. 1 that it had come across an Islamist message board posting predicting release of an audiotape. It said: "One of the brothers is going to post links to a new audiotape by Sheikh Osama Bin Laden, God Protect and Support him. He shall do so after the sunset prayer, Saudi time."

Staff writers Mike Allen, Nora Boustany and Susan Schmidt and researcher Julie Tate contributed to this report.

Osama bin Laden, in a videotape broadcast on al-Jazeera, told Americans not to elect any president who would try to destroy al Qaeda. Democrat John F. Kerry, campaigning in West Palm Beach, Fla., called Osama bin Laden and other terrorists "barbarians" and vowed to hunt them down.While campaigning in Toledo, President Bush told reporters that "Americans will not be intimidated or influenced by an enemy of our country."