According to news media calculations, the number of U.S. troops killed in Iraq has hit the 2,000 mark - a tragic milestone that is provoking new debate over the war and its aims.  The death toll is far less than other wars in U.S. history, though it is higher than recent conflicts such as the 1991 Gulf War. 

U.S. specialist Bernard Ceo was killed in Iraq two weeks ago, and nothing will be the same again for his father, Fred. "It takes a big piece out of you," he said.  "I thought we would have more time together."

The tragedy of the Ceo family has been experienced by many others as the American death toll reached 2,000 since the start of the war in March 2003. 

Despite the losses, President Bush has vowed not to change course.  Speaking to U.S. military families Tuesday, Mr. Bush said the United States must complete its mission in Iraq. "Each loss of life is heartbreaking," said the president, "and the best way to honor the sacrifice of our fallen troops is to complete the mission and to lay the foundations for peace by spreading freedom."

U.S. casualties have been on the rise as insurgents have become more adept at setting off roadside bombs.  These improvised explosive devices, some set off by cell phones, have become more sophisticated - causing more than half of all American fatalities over the past 31 months. 

This insurgent tactic - while sometimes successful - is a sign of weakness, according to James Phillips of the conservative Heritage Foundation.

"I think if you look at the breakdown of the deaths, most of them have been in bomb attacks, less and less are from actual guerrilla attacks and that tells you that the insurgents are becoming smarter but also they realize it is suicidal for them to attack the U.S. directly," said Mr. Phillips. "It's more and more of a terrorist campaign rather than a true guerrilla war campaign."

But the continuing violence and American casualties are having an effect on American public opinion, and reaching the 2,000 death threshold has given new impetus to the anti-war movement. 

In Washington, anti-war activist Cindy Sheehan, whose son was killed in Iraq, is holding a vigil in front of the White House to protest the war. "Not one person should have died, now we're up to 2,000," she said. "We need to bring our troops home as soon as possible."

Divisions over the war were evident when Senators observed a moment of silence Tuesday to honor the fallen.  Senate Republican leader Bill Frist and Democrat Dick Durbin responded differently to the sacrifice.

Bill Frist: "We offer our continued support, our continued prayers.  We pledge to stand firm in the war on terror."

Dick Durbin: "America can't allow the nation to drift into war without end in Iraq."

In Iraq, news of the 2,000-death milestone was widely publicized - but another figure looms much larger: the number of Iraqis killed since the U.S. invasion.  No one knows the exact number, but estimates put the toll at roughly 30,000. 

Researcher Nina Kamp at the Brookings Institution works on the Iraq Index, a statistical compilation of public opinion, economic and security data. 

She says the numbers give a mixed picture about the war. "In terms of security, there's very little good news in general because of the casualties of both Iraqis and Americans," said Ms. Kamp. "In terms of economics, probably a little more mixed. While there are many positives, the expectations are not being met so that category is probably a little bit on the negative side but much better.  So in general, I don't want to say the war is a disaster and not going well. But I think the current indicators are not particularly positive."

But others see progress in the recent Iraqi constitutional referendum and other developments.  Again James Phillips, "We're only 2 ½ years after the U.S. intervention and already we have a constitution and a transitional government and soon we'll have a permanent government.  If you look at that in historical terms that is moving incredibly fast, and in historical terms 2,000 deaths in a war is relatively small."

But for the families, each loss will always loom large.