Far from creating a Western-oriented regional anchor that would help spread democracy and curb terrorism throughout the Middle East and the Islamic world, as the president hopes, the United States finds itself battling increasingly sophisticated attacks from what analysts suspect is a combination of Iraqi and foreign militants.
With the view spreading that the current force of nearly 150,000 U.S. troops is not enough, pressure is building on Washington to "internationalize" the occupation of Iraq and share the burden with major Western countries such as France and Germany. This would likely require a new U.N. Security Council resolution that would dilute American power in Iraq, an idea opposed by Bush administration hard-liners.
The Baghdad bombing coincided with setbacks to American policy in Afghanistan, where suspected Taliban fighters or their supporters have mounted a series of deadly attacks in recent days, and in the Israeli-Palestinian arena, where a bus bombing in Jerusalem on Tuesday killed 20 people and imperiled U.S.-led peace efforts.
Bruce Hoffman, an expert on terrorism who heads the Washington office of the RAND Corp., a security-oriented think tank, said the Jerusalem suicide attack may have been timed by Palestinian militants to capture some of the limelight on the day of the truck bombing at the U.N. complex in Baghdad.
Beyond the timing, however, most experts see little connection. The Israeli-Palestinian conflict, they say, operates on its own momentum regardless of wider regional developments.
There may be an indirect link between the violence in Iraq and that in Afghanistan, in that both have roots in the U.S.-backed jihad fought throughout the 1980s to expel Soviet forces from Afghanistan.
Osama bin Laden, a veteran of that holy war, later adopted Afghanistan as a base for training camps for his al-Qaida terror network. Al-Qaida has encouraged Islamic holy warriors to confront U.S. forces in Iraq.
Hoffman, noting estimates that 70,000 to 120,000 holy warriors have passed through al-Qaida camps in Afghanistan, Sudan and Yemen, said they formed an "enormously amorphous," yet lethal, pool of recruits.
"It's clear that in the same way that Afghanistan became a rallying point [during the 1980s], we're in danger of Iraq assuming the same type of focus and the same type of rallying call to resist U.S. imperialism," Hoffman said.
Islamic militants crossing the Iraqi border from Saudi Arabia, Syria and other countries are among the possible suspects in Tuesday's bombing in Baghdad, a U.S. official said. Others are remnants of Saddam Hussein's Baathist regime and the radical Kurdish group Ansar al-Islam, which U.S. officials say has links to al-Qaida.
"It's also possible there are other groups. At this point we don't know," a U.S. official said.
What is clear, however, is that the violence in Iraq is taking on more varied aspects and becoming a more tactically sophisticated challenge to U.S. forces trying to stabilize the country.
"In my view, the resistance is acquiring more texture than it had a few months ago," said Kenneth Katzman, a terrorism expert at the Congressional Research Service. "There are substantially more dimensions to the resistance."
As recently as the first week of August, the Bush administration tended to describe the attacks as coming from hostile leftovers of a toppled regime out to target U.S. successes in Iraq. Secretary of Defense Donald H. Rumsfeld referred to them repeatedly as "dead-enders."
In doing so, the administration underestimated the continuing danger in Iraq, Hoffman said, much as other nations after earlier wars failed to pay sufficient heed to threats posed by hostile local forces.
"Historically, no matter what country has been confronted by this threat, it has dismissed and denigrated it as sporadic and uncoordinated - dead-enders - only to see it fulminate and explode into something far more serious," he said.
Amid finger-pointing over who is to blame for the failure to secure the U.N. mission in Baghdad, the chief U.S. administrator for Iraq, L. Paul Bremer III, insisted yesterday that Iraq was not in chaos.
The Pentagon, meanwhile, resisted calls from members of Congress for an expansion of the U.S. troop presence in Iraq.
"The conclusion of the responsible military officials is that the force levels are where they should be," Rumsfeld told reporters during a visit to Honduras. "The effort should be on developing additional Iraqi capability rather than additional coalition capability."
But Sen. John McCain, an Arizona Republican on a congressional mission in Iraq, told reporters in Baghdad, "After an event like this [the U.N. bombing], we have to evaluate whether we have enough people, whether we have the right kind of people and whether we are spending enough money, and I think it's appropriate to make that evaluation."
Britain, America's strongest ally, is renewing its push for broader international participation in Iraq. Headed for meetings at the United Nations, Foreign Secretary Jack Straw said yesterday that he had spoken to Secretary of State Colin L. Powell about securing a broader Security Council mandate that would give the world body a stronger role in Iraq.
In an interview with the British Broadcasting Corp., Straw acknowledged that Britain and the United States had failed to anticipate the security vacuum that developed in Iraq after the fall of Hussein's government.
Anthony Cordesman, a Middle East specialist at the Center for Strategic and International Studies, warned yesterday of the risk of "an unstable, unworkable nation-building process in central Iraq well into next spring, plus the constant risk of Shiite Islamists coming in."
Costs of the U.S. occupation, he said in an e-mail essay, "can easily rise from roughly $4 billion a month to at least $6 billion."
In a letter to Bush, Senate Foreign Relations Committee members Joseph R. Biden Jr., a Delaware Democrat, and Chuck Hagel, a Nebraska Republican, wrote: "Many foreign leaders whose people opposed the war need the political cover of a new U.N. resolution and a broader U.N. role to justify greater involvement in Iraq. It is worth enhancing the role of the United Nations because it will allow us to share the huge risk and expense of securing, policing, and reconstructing Iraq - tasks that will take tens of thousands of troops and tens of billions of dollars over many years."