U.S. intelligence analysts believe Osama bin Laden has shifted from outright calls for violence to political arguments in recent taped messages in hopes of driving a wedge between the United States and its allies, officials said Tuesday.

　　The analysts believe bin Laden is making the tactical shift to try to exploit some allies' concerns with U.S. policy in the Middle East and to attract more moderate Muslims who distrust the United States but have not embraced al-Qaida's violence, the officials said.

　　One U.S. official, speaking on condition of anonymity, said the CIA's technical analysis of a two-minute, five-second tape that surfaced Monday concluded with "moderate confidence" that the voice is likely bin Laden's.

　　Poor audio quality made it difficult to reach a more certain conclusion, but U.S. officials are operating under the assumption that it is bin Laden's voice. That tape formally names Abu-Musab al-Zarqawi as al-Qaida's leader in Iraq and tries to persuade Muslims not to vote in the Iraqi elections set for Jan. 30.

　　Al-Zarqawi has captured worldwide attention for several beheadings of hostages.

　　The official said U.S. intelligence analysts detected a notable change in messages from bin Laden and deputy Ayman al-Zawahri in 2004, with fewer threats and specific emphasis on offering political arguments against U.S. policy toward Muslims and the Middle East.

　　Analysts believe al-Qaida's leadership has "attempted to hone their political message in an effort to persuade the world to rally to their cause. They have gone to great lengths to explain al-Qaida's objections to the West. And this message specifically seeks to isolate the United States from its allies," the official said.

　　Officials caution, however, that the change in tactic doesn't mean al-Qaida or its allies have foresworn violence. U.S. intelligence continues to gather evidence showing the group's intention to strike Americans, including a recent attack on a U.S. diplomatic post in Saudi Arabia.