Answering Osama bin Laden's call for holy war in Iraq, hundreds of followers from at least eight nations have entered the country and are playing a major role in attacking Western targets and Iraqi civilians, U.S. and Iraqi officials say.

Operatives of the Al Qaeda terrorist network and affiliated extremist groups are collaborating with Saddam Hussein loyalists, officials say, forming an array of shadowy alliances that are emerging as one of the biggest challenges to U.S.-led efforts to bring stability to the war-torn country.

Some officials believe that Iraq is replacing Afghanistan as the global center of Islamic jihad and becoming the prime locale for extremist Muslim fighters who are eager to confront Americans on Arab soil.

As many as 2,000 Muslim fighters from as far as Sudan, Algeria and Afghanistan are operating in Iraq, officials say. Ansar al Islam, an Iraqi group that was previously active in northern Iraq, also has made a comeback, officials say. The Bush administration says Ansar has ties to Al Qaeda.

Shocked and angered at an apparent suicide bombing against Muslim families in the midst of the holy month of Ramadan, ordinary Saudis said the bombing on Sunday would destroy any lingering support for Muslim militants.

Bombarded by brutal television and newspaper images of carnage caused by a midnight explosion at the housing compound of Muhaya, on Riyadh’s desert outskirts, many were united in condemning the second deadly attack in their capital in six months.

"What Islam is this? They are terrorists," said Hamdan Youssef, a 39-year-old businessman.

The attack came almost six months to the day after May 12 suicide bombings in Riyadh — which Saudis describe as their own Sept. 11 — killed 35 people, including nine Americans.

"Despite losing three governorships in the past month, Democrats continue to insist that their strategy of running every election as a referendum on Bush is working." Even if it costs them a fourth governorship in Louisiana this week.