Updated

U.S. intelligence analysts believe Usama bin Laden (search) 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 Qaeda's (search) 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 (search) as Al Qaeda'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 Qaeda'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 Qaeda'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 Qaeda 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.

Experts say the noticeable change emerged last April in a bin Laden audio tape that offered a truce between Al Qaeda and any Western country that withdrew from fighting in Muslim countries.

Then, a videotape surfaced in October, shortly before the U.S. presidential elections, telling Americans they could spare themselves from future terror attacks if their country stopped threatening the security of Muslims.

Both tapes were in sharp contrast to the gun-wielding bin Laden seen in a 2003 videotape, vowing to strike again.

In Monday's tape, bin Laden makes an argument against Iraqi participation in next month's elections.

"In the balance of Islam, this constitution is infidel and therefore everyone who participates in this election will be considered infidels. Beware of henchmen who speak in the name of Islamic parties and groups who urge people to participate in this blatant apostasy," the speaker thought to be bin Laden said in the tape.

Roger Cressey, who was the deputy to former White House counterterrorism chief Richard Clarke in the Clinton and first Bush administrations, said the most recent message shows bin Laden trying to broaden his audience.

"He is trying to position himself as speaking to a global Islamic community in a way that further defines the fight against the West in his terms," Cressey said. "If he can show he's more than just a rank-and-file terrorist, that will help his message."

Cressey said bin Laden is trying to reach "the part of the Muslim world that is sympathetic to the message, but is not willing to endorse him. These are fence sitters, people who have serious problems with the U.S. policy but have not become activists against us yet."

This week's tape also provides fresh evidence that the leader of the bloody Iraqi insurgency has merged with the world's most famous terror group in a relationship that benefits both. Two months ago, al-Zarqawi renamed his group to add the name Al Qaeda.

U.S. intelligence analysts believe the merger "gives al-Zarqawi access to a broader network, more tools, resources, and the ability to plug into the established Al Qaeda revenues and assets," the U.S. official said.

Private security experts say bin Laden also benefits from allying himself with an anti-American fighter who gets daily publicity. But the alliance can also come at a price: Bin Laden is now tied to a man directing bomb attacks against Iraq's majority Shiite Muslims as well as Americans.

"Bin Laden gets the benefits of Zarqawi's notoriety," said Vince Cannistraro, a former CIA counterterrorism official. "He [al-Zarqawi] has got the pre-eminent insurgency in Iraq. He's the one who is the bloodiest, who carried out the most dramatic and public suicide bombings."

The difference between this and other bin Laden alliances, Cannistraro said, is that bin Laden — a Sunni Muslim — "has not been a vocal enemy against the Shiites. By adopting Zarqawi, he's taking that whole package, someone who is virulently anti-Shiite."

Ben Venzke, president of the private IntelCenter in Alexandria, Virginia, and a government consultant, said bin Laden's taped messages show "Al Qaeda is very savvy when it comes to understanding public perception, its media campaign and messaging and its image."

Peter Bergen, a fellow at the New American Foundation, a Washington think tank, says the recent rash of messages from Al Qaeda also highlight the failure of the U.S. search for bin Laden. "The tapes are coming thick and fast, which means they [the terrorists] are feeling secure," he said.