A U.S. citizen accused of joining Al Qaeda and plotting to assassinate President Bush said in a videotaped confession that he was motivated by hatred of American support for Israel.

Ahmed Omar Abu Ali also said on the tape, played in court for the first time Tuesday, that a top Al Qaeda operative in Saudi Arabia (search) "made it clear I became one of them and that I could speak in the name of Al Qaeda."

The 13-minute confession was videotaped in 2003 by authorities in Saudi Arabia, where Abu Ali attended college.

His attorneys want the confession thrown out. They argue that the 24-year-old falsely confessed after being tortured and whipped by the Saudis, and they say U.S. authorities were complicit in the torture. Prosecutors deny Abu Ali (search) was mistreated.

U.S. District Judge Gerald Bruce Lee (search) viewed the videotape Tuesday over defense objections, saying he wanted to observe Abu Ali's demeanor.

At several points on the black-and-white videotape, Abu Ali could be seen yawning and chuckling to himself. When he discussed his training with a Kalashnikov (search) rifle, he pantomimed a rifle attack.

Other parts of the tape appeared to be a monotone regurgitation of a statement that prosecutors have acknowledged was written for him by the Saudis. Prosecutors also have said he was given an opportunity to revise the statement.

In the confession, Abu Ali says he "was interested in jihad and the idea of mujaheedin" because of "my hatred of the United States for support of Israel against the Palestinian people."

He said he discussed numerous possible terrorist acts with two Al Qaeda leaders in Saudi Arabia, Ali abd al-Rahman al-Faqasi and Sultan Jubran Sultan al-Qahtani. They encouraged him to return to America, integrate into society and establish an Al Qaeda cell, he said.

Abu Ali said he favored the idea of assassinating Bush rather than attacks on military targets or plane hijackings "because it would be easier to carry out because he appears in so many public places."

Prosecutors allege that Abu Ali, who grew up in Virginia, joined Al Qaeda while in Saudi Arabia and confessed to plotting terrorist acts, including assassinating the president and U.S. senators.

He is charged with conspiracy to assassinate the president, conspiracy to commit aircraft piracy and contributing services to Al Qaeda, and could face life in prison if convicted.

The defense argues that U.S. authorities worked with the Saudis to investigate and denied Abu Ali's constitutional rights to an attorney and to remain silent. Several FBI agents testified Tuesday that the Saudis investigated and interrogated Abu Ali on their own.

The pretrial hearing on the validity of Abu Ali's confession is expected to continue into next week.