BAGHDAD, Iraq -- With the grim milestone of the 2,000th U.S. military death looming in Iraq, many wonder about the direction of the insurgency that killed most of them.
Experts think the country's increasingly regional-oriented politics will fuel the insurgency and even spread it further inside Iraq.
Others put forward a simple, disquieting scenario: So long as U.S. and other foreign troops remain in Iraq, the insurgency will continue.
A roadside bomb struck a car being driven by a police colonel in northern Iraq on Sunday, killing him and his two sons as well as two young girls nearby, and insurgents killed more than 15 other Iraqis in shootings, bombings and suicide attacks.
Five U.S. soldiers were wounded in three bombings in the capital. The attacks came after a week in which 23 U.S. troops were reported dead, raising to 1,996 the number of military personnel killed since the war began, according to an Associated Press Count.
Also Sunday, the U.S. military confirmed that insurgents killed four American contract workers and wounded two last month when their U.S.-escorted convoy got lost in a town north of Baghdad.
The 2,000 mark in U.S. military deaths is approaching at a time when Iraqi and U.S. officials are congratulating themselves that the Oct. 15 constitutional referendum and the start of Saddam Hussein's trial four days later passed without major bloodshed and destruction.
They also are upbeat about the growing efficiency and number -- 200,000 at present -- of Iraq's security forces, although some U.S. commanders say the Iraqis need 18 months to two years before they can fight the insurgency unaided.
Recent operations in western Iraq, especially in towns along the Euphrates River close to the Syrian border, are said to have been effective in disrupting the insurgents' supply lines and reducing the number of car bombs.
Stepped-up security has forced insurgents in recent weeks to largely abandon using car bombs and resort to indirect fire, such as lobbing mortar shells from afar, Interior Minister Bayan Jabr said.
Maj. Gen. Rick Lynch, U.S. military spokesman in Iraq, said troops captured more than 300 foreign fighters and killed 100 members of al-Qaida in Iraq the past six months. Other successes include the detention of 600 insurgents in the two weeks before the referendum, said Maj. Gen. William G. Webster, commander of U.S. forces in Baghdad.
But no official predicts a quick victory.
"The insurgents are still there," Lynch cautioned. "They still want to derail the democratic process. They still want to discredit the Iraqi government, so operations continue."
Last week proved to be one of the bloodiest for U.S. troops, with 23 killed, many in restive Anbar province. That raised to 1,996 the number of U.S. military personnel who have died since the war began in March 2003, according to an Associated Press Count.
The insurgents are made up of disparate groups of Sunni Arabs, who lost the privileged status they held under Saddam. But the motives driving them are many, from a nationalist anger over the presence of foreign troops to an urge to create an Islamic state to a desire to regain perks.
The domestic rebels are aided by foreign fighters brought into Iraq by leaders like al-Qaida in Iraq's Jordanian-born Abu Musab al-Zarqawi to participate in a self-styled "holy war." The foreign contingent, said by U.S. officials to be mostly Arabs, is widely blamed for dozens of devastating suicide bombings targeting Shiite Muslims and Iraqi security forces.
Iraq's majority Shiites and minority Kurds -- the two communities most oppressed under Saddam -- have been empowered by the former dictator's ouster and are cooperating with the Americans.
Their areas, in the south and north, are almost entirely free of the violence that grips regions with significant Sunni Arab populations.
But experts contend the fighting could soon begin to take dramatic turns, more heavily influenced by outside events and possibly bringing new factions into the fight.
For example, they say, if Washington and London continue to put pressure on Iran over its nuclear program, Iraq's Shiite neighbor could be tempted to encourage radical Iraqi Shiite factions to stage attacks on U.S. and British forces.
Indeed, British Prime Minister Tony Blair said recently the bombs that killed eight British soldiers in southern Iraq since May were similar to those used by Hezbollah, the Iranian-backed Shiite militant group in Lebanon.
Iran, which has close links to Shiite political parties in Iraqi Prime Minister Ibrahim al-Jaafari's coalition government, has denied any involvement.
"The Iranians are instrumental in upping the ante," said Vali Nasr, who lectures on national security affairs at the U.S. Naval Postgraduate School in Monterey, Calif. "They have been practicing restraint, but this may already have begun to change."
Nasr said Iraqi Shiites' tolerance of the U.S. military presence flows from Washington's support for the political process that has benefited them the most. But, he said, this could change if it appeared the United States was not leaving Iraq.
U.S. forces already had a taste of simultaneously fighting Sunni Arabs and Shiites. For nearly five months last year, U.S. forces were stretched to the limit, fighting the mainstream insurgency in Sunni areas while struggling to put down two rebellions by Shiite militiamen loyal to radical Shiite cleric Muqtada al-Sadr.
Syria, another neighbor, could succumb to mounting U.S. pressure to keep Islamic fighters from using its territory to cross into Iraq. But it also could respond by seeking to create more problems for the Americans by helping the militants to join the Iraq war.
"As long as there are Americans in Iraq, Islamists will want to go and fight them," said Dia'a Rashwan, an Egyptian expert on Muslim militant groups.