WASHINGTON — Egypt's revolution, a secular popular revolt that used nonviolent means to humble an entrenched autocrat, will remake the Middle East — and could mark the end of the era that began on Sept. 11, 2001, according to U.S. officials, former officials and analysts here and in the Middle East.

If the Egyptian revolution delivers on its promise of a march toward democracy, the protesters in Tahrir Square will have dealt a stunning blow to al Qaida and other radical groups, whose propagandists argue that their way — violence and a puritan form of Islam — is the only way to save the Muslim world.

If the most populous Arab state slips back into a new dictatorship or anarchy, however, extremists could find a fresh foothold and a new lease on life in an Arab population that polls show has largely rejected them.

The stakes for the U.S. in a region that has long bedeviled it are stratospheric.

"The Egyptian revolution could be a huge defeat or a huge victory for al Qaida. It depends what happens," said Kenneth Pollack, a former CIA and White House official who's now director of the Brookings Institution's Saban Center for Middle East Policy. If things turn out well, "It could destroy their narrative," he said.

CIA Director Leon Panetta told Congress Thursday, before Mubarak's departure was official, that the events in Egypt "will have tremendous impact. If it's done right, it will help us a great deal in trying to promote stability in that part of the world. If it happens wrong, it could create some serious problems for us and for the rest of the world."

In the short-term, the exit of the 82-year-old Egyptian President Hosni Mubarak puts new pressure on other long-sitting rulers to reform or meet a similar end.

While the ouster of governments first in Tunisia and then Egypt wasn't predicted, analysts say that rulers in Arab republics — and particularly Algeria and Yemen — have more to fear than the hereditary monarchies in Jordan and the energy-rich Persian Gulf.

"Reform or revolution. Reform or rebellion. Reform or the entire regime can collapse," said Shafeeq Ghabra, a political science professor at Kuwait University.

Ghabra said Mubarak's removal will empower Arab nations' bulging youth populations to speak out. He spoke by phone Friday from Morocco, where he said many were cheering Mubarak's departure.

The pro-democracy movements are a "repudiation first and foremost of authoritarianism, of the leader functioning without sanction from the people. The former model" is what produced al Qaida leaders Osama bin Laden and Ayman al Zawahiri, said Nubar Hovsepian, an Egyptian-born political scientist at Chapman University, in Orange, Calif.

For the Obama administration's Middle East policy, major change is in the offing, too. President Barack Obama, who has emphasized Israeli-Palestinian peace talks and Iran's nuclear program, will be forced to invest much more time and resources in democracy promotion and supporting Egypt's uncertain transition.

Advocates say that Obama cut funding for democracy initiatives in Egypt and elsewhere, and gave too little attention to the issue after delivering a major speech in Cairo early in his presidency.

"The question mark is now, are they going to get it?" Pollack said. "Let's not wait until the next revolution" to push for democracy and openness, he said.