BAGHDAD, Iraq — As 2006 came to an end, the steadily rising toll of U.S. troops killed in Iraq hit another grim milestone — 3,000 dead.

The latest marker came yesterday as President Bush prepared to lay out his proposals for changing the U.S. strategy in Iraq. Bush has been meeting with advisers at his ranch in Crawford, Texas, and White House officials have said he could announce his plans this week.

Bush appears to be leaning toward a troop increase. Some advisers believe sending more troops could allow U.S.-led forces to tamp down the sectarian war that the Pentagon has identified as the main source of instability in Iraq.

Others, including some ranking U.S. commanders and many members of Congress, believe that sending more U.S. troops to Iraq would only worsen the situation by reducing the pressure on Iraq's warring parties to settle their differences.

Asked about the latest death toll, White House spokesman Scott Stanzel said Bush "grieves for each one" and "will ensure their sacrifice was not made in vain."

PATROLS INCREASED

Since the summer, U.S. commanders have increased the number of troops in Baghdad in an effort to quell the civil war here with stepped-up patrols. That effort has had little impact on the violence but has increased the number of U.S. troops killed in the capital.

In that regard, the most recently announced deaths were typical of many in recent months: The Pentagon said that Spc. Dustin R. Donica, 22, of Spring, Texas, had been killed Thursday by small-arms fire in Baghdad. The U.S. military command here announced that another, still unidentified, soldier had died Saturday, also in the capital, when a roadside bomb exploded near his patrol. The military typically delays announcements of deaths to allow relatives to be notified first.

Overall, the rate of military fatalities has remained relentless for more than 2 1/2 years, since the insurgency against the U.S. occupation of Iraq began to pick up strength in 2004. The U.S. invasion in the spring of 2003 took the lives of 140 American troops, then, after an initial lull, the 1,000th death was announced in September 2004 and the 2,000th in October 2005.

U.S. casualties continue to be eclipsed by the death toll among Iraqis. At least 5,900 Iraqi police and soldiers have died since 2003, according to the Iraq Index, a database issued by a Brookings Institution think tank. Estimates of civilian death tolls have ranged widely, from tens of thousands up to more than half a million.

The 3,000th U.S. military death comes in the wake of the execution of deposed president Saddam Hussein, an event that military leaders believe will lead to more attacks against U.S. troops, at least in the short run.

DEATHS DOWNPLAYED

The U.S. military took no official notice of the 3,000 figure, and some commanders played down the number of fatalities. U.S. Marine Corps Commandant Gen. James Conway said in an interview that, given the significance of Iraq and Afghanistan to U.S. national security, the death toll in those two countries has not been excessive. On average, slightly more than two U.S. troops die in Iraq every day, compared with 300 or more a day during World War II, he said.

But the intensity of the fighting and the sense that many American troops are caught in the crossfire of a civil war have helped undermine public support for the war. Yesterday, two prominent Republican senators said in television interviews that they were hesitant to send more U.S. troops to Iraq.

"The administration needs to identify precisely where the battle lines are — who is it we combat. I haven't seen such lines," said Sen. Richard Lugar of Indiana, chairman of the Senate Foreign Relations Committee.

Sen. Arlen Specter, who just returned from a trip to the Middle East, said he, too, had not seen the administration lay out a compelling case for troop increases. Lugar spoke on "Fox News Sunday," Specter on CNN's "Late Edition."

DECEPTIVELY INTENSE WAR

Anthony Cordesman, a military expert at the Center for Strategic and International Studies in Washington, said in a public letter last week that the fighting is more intense than the death toll implies.

New protective measures and advances in military medicine reduce the number of deaths, but not the difficulty of the war, he said, noting that the total of U.S. killed and wounded reached 25,000 in mid-December.

More than 24,800 additional troops sustained noncombat related injuries — illnesses, and vehicle crashes and other accidents — serious enough to require air transport.

And attacks against U.S. and Iraqi security forces are increasing. The military does not release specific numbers, but the Iraq Study Group reported last month that total attacks averaged 180 per day in October, up from 70 per day last January.

Military commanders agree that the number of U.S. deaths would be far greater but for improved defenses, such as armored Humvees and a variety of signal jammers to stop remotely detonated roadside bombs.

INSURGENTS ADAPTING

Many U.S. troops are wearing more body armor, adding bullet-resistant plates to protect their sides and high Kevlar collars to cover their necks.

But the insurgents also adapt. In Kirkuk, some U.S. military mess halls have posted boards showing the different types of wires insurgents use to detonate bombs manually and avoid signal jammers. "They morph based on our operations," said U.S. Col. Patrick T. Stackpole, an Army brigade commander in Kirkuk. "They're constantly changing up their ability to get money, to get different types of weapons, their tactics with IEDs, with small-arms fire. They adapt to any new technique."

The most dangerous part of Iraq for U.S. troops remains Anbar province in the western deserts, where more than 1,000 U.S. troops have died since 2003.

The 2nd Battalion, 3rd Marine Regiment, out of Marine Corp Base, Hawai'i, has been deployed to Anbar since August; at least 19 Marines from that battalion have died.

The 3rd Battalion, 3rd Regiment, also out of Kane'ohe Bay, was sent to Anbar in March. It suffered 11 deaths in its seven-month deployment.

Almost 800 troops have died in Baghdad. The third worst province is Salahuddin, where nearly 300 U.S. troops have died — and where Saddam's body was buried yesterday.

At least 111 American troops were killed in December, making it the deadliest month for U.S. forces since the battle for Fallujah in November 2004. Overall, at least 820 U.S. military personnel were killed in 2006.