Reunified Islam: Unlikely but Not Entirely Radical

But while Turks won self-rule, most of the former caliphate was divided among European colonial powers. One Arab scholar called it "the division of Muslim lands into measly pieces which call themselves nations."

This is what inspired the group most directly focused on the push for a new caliphate, Hizb ut-Tahrir, or Party of Liberation. The group, which claims to be active in 40 countries, began in 1953 as an offshoot of the Muslim Brotherhood. But while the Brotherhood, which also favors a caliphate, embraced realpolitik, growing into a potent opposition force in Syria and Egypt, Hizb ut-Tahrir charted a more subversive path.

Of Coups and the Caliphate

"For a long time nobody heard of HT. They were underground," said Kian Schmucker, a Copenhagen city council candidate passing out leaflets outside a rare public meeting of Hizb ut-Tahrir. On a cloudy Sunday in November, about 800 young Danes, mostly the children of Muslim immigrants, were crowding into a civic sports hall. The first presentation: graphic images of dead Iraqi children.

"No one can doubt that the declared war on terrorism is a war on Islam," Fadi Abdullatif, a local Hizb ut-Tahrir spokesman, declared from the podium as the videotape ended. "This Islamic state is the only protection, the only shield for the Muslims."

The chorus of " Allahu akbar! " -- God is great -- was led by ardent young Europeans, a handful of converts in an attentive audience segregated by gender: fashionably dressed young men on the right, women in head scarves on the left.

For four hours they heard Hizb ut-Tahrir's disciplined, intensely argued belief that the Muslim world lost its moorings when it imported not only scientific advances from the West, but also systems such as nationalism and democracy that emerged at the same time. In a series of 22 volumes on sale beside the podium, and in weekly discussions, the group sketches an alternative governing system it believes lies embedded in the Koran and the teachings of the prophet.

The system includes a caliphate, revived after national governments are subverted by Hizb ut-Tahrir members working in their highest levels, according to the plan. Hizb ut-Tahrir members have been charged with planning such coups in Jordan and Egypt. Zeyno Baran, an analyst at the Washington-based Nixon Center who has written extensively on the group, said it could "usefully be thought of as a conveyor belt for terrorists."

The group has a rigid, cellular, secretive structure and a bookish set of beliefs describing its utopian vision for a future caliphate. Hizb ut-Tahrir insists it has renounced violence, a policy that differentiates it from groups such as Kaplan's motley band or the Chechen guerrillas who carried out the deadly 2004 siege at a primary school in Beslan, in southern Russia -- and who would seat a caliph in the northern Caucasus, according to Chechen guerrilla groups' Web sites.

Al Qaeda thrived in Afghanistan when the Taliban leader, Mohammad Omar, was called "Commander of the Faithful," a caliphic title. In his book published online shortly after Sept. 11, bin Laden's deputy, Ayman Zawahiri, declared that terror attacks would "be nothing more than disturbing acts, regardless of their magnitude" unless they led to a caliphate in the "heart of the Islamic world."

The American-led invasion of Iraq provided an opportunity to do just that, Zawahiri apparently wrote last year to Abu Musab Zarqawi, the Jordanian who heads the insurgent group al Qaeda in Iraq. In the version of the letter posted on a U.S. government Web site, Zawahiri said only the presence of foreign occupiers had stirred "the Muslim masses" to action. He advised Zarqawi to use Iraq's Sunni areas as the base for "an Islamic authority or emirate, then develop it and support it until it achieves the level of a caliphate."

The letter, which Bush has paraphrased at length, also calls for attacking Israel "because Israel was established only to challenge any new Islamic entity."

"This is something that is characteristic of our time, to reestablish an ideological empire," said Serif Mardin, a leading Turkish scholar on political Islam. "A sweet caliph of ancient times is overwhelmed by this modern military idea. I mean, the caliph is supposed to be a nice guy.