"EACH LOSS of life is heartbreaking," President Bush said Tuesday, as the 2,000th death of an American soldier in Iraq was recorded. That is surely one thing about which everyone in an increasingly bitter and polarized debate regarding the war can agree. The sacrifice of American lives, and the debilitating injuries suffered by thousands of others, have devastated families and wounded the nation. That the totals are relatively small compared with those of previous U.S. wars, or the tens of thousands of Iraqis who have died, does not change that.

What does matter is what has come from those sacrifices. The most brutal and dangerous dictator in the modern history of the Middle East was deposed, and last week he was put on trial before an Iraqi court. Millions of Iraqis he oppressed continue to be grateful for their liberation; unlike most Americans, they still believe that the invasion was worth the cost. Despite the continuing insurgency, more than 60 percent of registered voters turned out this month for a constitutional referendum, and slates are forming for a parliamentary vote in December that could be the most inclusive, competitive and meaningful election ever held in the Arab world.

That the war remains broadly unpopular among Americans, and is routinely and glibly described as a catastrophe by administration critics, shows that these achievements are cloaked by the continuing bloodshed. The horrific nature of car bomb and suicide attacks on U.S. soldiers and innocent civilians has compounded the effect of the loss of life. So have the failure to find weapons of mass destruction -- the threat that originally appeared to justify the costs and risks of an invasion -- and the seeming intractability of the insurgency, which has survived countless military offensives, killings or arrests of top leaders, and changes of tactics. The political gains, though real, have been undermined in recent months by the sectarian and ethnic polarization of Iraqis and the apparent effort by a number of Shiite and Kurdish political leaders to carry out a de facto partition of the country under the guise of "federalism." That agenda, and the Bush administration's weak response to it, threatens to tip Iraq into a full-scale civil war, with U.S. troops caught in the middle.

There are no easy solutions to these problems, nor is there a quick way to end American losses. In fact, one of the greatest dangers of Iraq is that domestic disenchantment with the mission will lead to a premature withdrawal of U.S. troops, a step that would greatly increase the carnage and hand a major victory to this country's foremost enemy, the Islamic extremist movement headed by al Qaeda. Mr. Bush could have avoided much of that disillusionment had he been more honest with the country from the beginning about the likely costs of the war. Yet even now he refuses to speak candidly about the conflict; he describes it as if it were exclusively a battle between U.S.-backed democrats and foreign terrorists, rather than a complex political and military struggle among Iraqis. He did say on Tuesday that "this war will require more sacrifice, more time and more resolve." As U.S. servicemen continue to give their lives, the president must explain more clearly and more honestly why that is so -- and why it is necessary.