An American jihadist tied to Al Qaeda has released an extremist audiotape attacking President Obama, calling for American Muslims to leave the U.S. and join the armed Islamic struggle around the world.

Abu Mansoor al-Amriki, an apparent American citizen, is a member of the Somalia-based Islamist militant group al-Shabaab and speaks in English with a flat American accent addressing American Muslims.

Titled "A Response to Barack Obama: The Beginning of the End," the tape is a belated reply to Obama's speech in Egypt addressed to the Muslim world. In it, Abu Mansoor praises Osama bin Laden and refutes various points Obama made during his speech from Cairo.

Abu Mansoor al-Amriki (the American) has raised his profile in recent months, and followed in the footsteps of the better known Adam Gadahn, an American al Qaeda operative based in Pakistan. Gadahn is wanted by the FBI, and the State Department has offered a $1 million reward for his capture. Abu Mansoor has not risen to that level of infamy yet, but appears to be making efforts to land on the notorious Rewards for Justice list. Abu Mansoor first appeared in a September 2007 video that aired on al-Jazeera. Near the end of the message, Gadahn and three other apparent Americans jihadists are shown.

In recent months, Abu Mansoor has released tapes that included American rap lyrics in the background. According to Ben Venzke, president of IntelCenter, a Washington-based firm that tracks and analyzes al Qaeda propaganda videos, Mansoor and al Shabaab have released a "steady, yet rapid, escalation in the overall video production quality of their material."

U.S. government officials have been concerned about the growing attraction for American citizens of Somali decent heading to Somalia to join that country's continuing civil war and insurgency. Last year, FBI officials acknowledged that as many as 20 Somali-American teenagers disappeared from their Minneapolis community, headed to fight with the al-Qaeda-linked group al Shabaab.

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