Beirut, Lebanon ? In a videotaped message apparently aimed at influencing the U.S. presidential election, Osama bin Laden laid out his reasons for organizing the Sept. 11 attacks and chastised President Bush for his response that day.

For the first time, bin Laden claimed responsibility in the tape aired Friday for ordering the Sept. 11, 2001, attacks. He did not directly threaten new attacks, but said, “there are still reasons to repeat what happened” because of U.S. policies in the Middle East. He addressed his comments directly to the American people, saying he wanted them to learn how “to avoid another Manhattan.”

“Your security is not in the hands of Kerry, Bush or al-Qaida. Your security is in your own hands,” bin Laden said in formal Arabic on the 18-minute tape, portions of which were aired on the Al-Jazeera satellite TV network. “Every state that does not interfere with our security has naturally guaranteed its own security.” The tape appeared to have been produced Sunday, according to a U.S. official familiar with the CIA’s preliminary assessment.

Bin Laden offered the fullest explanation to date for why he decided to target the World Trade Center. He claimed he was motivated by the Israeli invasion of Lebanon in 1982, an event he had referred to in previous statements but had never assigned such a central role in his thinking.

“After our patience ran out and we saw the injustice and inflexibility of the American-Israeli alliance toward our people in Palestine and Lebanon, this idea came to my mind,” he said. “When I saw those destroyed towers in Lebanon, it sparked in my mind that the oppressors should be punished in the same way and that we should destroy towers in America — so they can taste what we tasted and so they stop killing our women and children.”

Bin Laden noted that the U.S. Navy’s Sixth Fleet was dispatched to Lebanon soon after the Israeli invasion. He did not mention the 1983 bombing of the U.S. Marine barracks in Beirut, which killed 241 troops and led to a U.S. withdrawal.

In 1982, bin Laden was 25 years old and fighting in the CIA-sponsored campaign to drive the Soviet Union from Afghanistan. The Israeli occupation of Beirut was significant for Arab nationalists because it marked the first time an Arab capital had fallen to Israeli forces, but it is not generally considered a seminal event for Islamic militants such as bin Laden.

Osama bin Laden speaks in this image made from an undated video broadcast Friday by Arab television station Al-Jazeera. In the video, bin Laden directly admitted for the first time that he carried out the Sept. 11 attacks.

On Friday’s tape, bin Laden also attacked former President George H.W. Bush, saying he became “enamored” of Arab regimes “half of which are ruled by militaries and the other half ruled by the sons of kings and presidents.” Bin Laden said the elder Bush “became jealous of how they can stay in their positions for decades, stealing the money of their people.”

Bin Laden accused the senior Bush of schooling his son in the corrupt ways of Arab rulers. “He transferred the abuse and limiting of freedoms to his son, who called it a Patriot Act under the pretense of fighting terrorism,” bin Laden said, adding that the elder Bush “also did not forget to transfer the experience of these rulers in cheating and fabricating, as his son did in Florida.”

Bin Laden spoke in a calm, measured tone, reading from a prepared text. He was behind a wooden table, unlike most of his previous videotapes, where he has usually sat cross-legged on the floor. He appeared healthy and wore a white turban and a traditional white robe with a golden cloak.

Analysts said bin Laden’s appearance was calculated to project an image of a political, rather than military, leader.

“He’s trying to appear like a modern leader. He’s sitting behind a table and not on the floor,” said Diaa Rashwan, a leading expert on Islamic militants at the Al-Ahram Center for Political and Strategic Studies in Cairo. “Unlike his previous tapes, he’s not speaking in a confrontational tone. His presentation is very important because it’s tied to his message: He wants to explain to the American people why he ordered the September 11 attacks and explain their consequences.”

Rashwan said the tape’s timing and bin Laden’s appearance and tone show he is trying to play a role in the U.S. election. “He is trying to influence the American voters,” Rashwan said. “He’s almost trying to present himself as a political analyst.”