( Reuter )- The White House, Pentagon and political leaders expressed sorrow on Monday as the number of U.S. troops killed in Iraq hit 4,000, days after President George W. Bush marked the fifth anniversary of the conflict.
Bush was saddened by the deaths and felt responsible for ensuring the United States was ultimately successful, the White House said after a roadside bomb in Iraq killed four U.S. soldiers, pushing the toll to a new milestone.
"It's a sober moment, and one that all of us can focus on in terms of the number of 4 ,000 ," White House spokeswoman Dana Perino said. Bush himself did not address the issue in public.
"The president feels each and every one of the deaths very strongly and he grieves for their families," Perino said. "He obviously is grieved by the moment but he mourns the loss of every single life."
Pentagon spokesman Bryan Whitman said: "Every single loss of a soldier, sailor, airman and Marine is keenly felt by us in the department, by military commanders, by families, friends, both in theater and here at home."
Precise Iraqi casualties in the conflict are not known but the widely cited human rights group Iraq Body Count said earlier this month that up to around 89,300 civilians have been killed since 2003.
Democratic political leaders also discussed the new milestone. Presidential contender Barack Obama paid tribute to the dead but said the war should never have been waged and troops should be brought home soon.
His rival, Hillary Clinton, said the United States honored the sacrifice of those killed and pledged to respond "by bringing a responsible end to this war, and bringing our troops home safely."
Recent public opinion polls show around 30 percent of voters approve of Bush's handling of the war and roughly the same number believe the loss of American life was worthwhile.
The 4,000th U.S. death came days after Bush marked the fifth anniversary of the war and said the United States was on track toward victory.
The president chaired a meeting of his National Security Council on Monday and was briefed by Ryan Crocker, the U.S. ambassador in Baghdad, and Gen. David Petraeus , the top U.S. military officer in Iraq.
Bush also was to receive Iraq briefings at the Pentagon on Wednesday, the White House said, ahead of April 8-9 when Crocker and Ryan testify to Congress.
Bush and his advisors are trying to decide whether to continue to reduce troop levels in Iraq after last year's surge, which is credited with lowering violence there.
Some experts are urging a pause in troop reductions to avoid losing the gains made in recent months.
The deaths that pushed the U.S. toll in Iraq to 4,000 happened as new violence burst out, including sustained mortar fire against the U.S. protected "Green Zone" in Baghdad.
Perino said Bush feels responsible for leading the United States into the war and also for ensuring it succeeds.
"One of the things that he hears from families of the fallen is that they want him to lead the country to complete the mission and he is committed to doing that," Perino said. "He wants them to know that their sacrifices will not be in vain."
Whitman said that despite the new casualties, violence overall was down compared to last year.
"Both coalition and Iraqi security force casualties are down significantly from about May of '07," he said. " Iraqi civilian casualties has also been on a downward trend since December of '06."
"Would we like to reduce the casualties to nothing? Of course we would. Are there still going to be casualties in the days ahead? Most unfortunately there will be."