(Adds quotes from Bush, Cheney, McCain)
March 24 U.S. leaders on Monday marked the passing of a new milestone in Iraq after the number of U.S. service members killed in the war reached 4,000.
Following are comments from presidential candidates, Bush administration officials and lawmakers on the war in Iraq.
PRESIDENT GEORGE W. BUSH
"One day people will look back at this moment in history and say 'thank God there were courageous people willing to serve' because they laid the foundation for peace for generations to come. ... I have vowed in the past and I will vow so long as I'm president to make sure that those lives were not lost in vain."
VICE PRESIDENT DICK CHENEY
"It places a special burden, obviously, on the families. We recognize, I think -- it's a reminder of the extent to which we're blessed with families who have sacrificed as they have. The President carries the biggest burden, obviously; he's the one who has to make the decision to commit young Americans. But we are fortunate to have the group of men and women, the all-volunteer force, who voluntarily put on the uniform and go in harm's way for the rest of us."
SEN. JOHN MCCAIN, PRESUMPTIVE REPUBLICAN PRESIDENTIAL NOMINEE
"My thoughts and my prayers go out to them (the families of the dead) every day, not just on the day that 4,000 brave young Americans are sacrificed."
"I wear a bracelet on my hand not only a symbol of the sacrifice that a brave young man named Matthew Stanley made, but that of 4,000 other brave young Americans who have served and sacrificed."
DANA PERINO, WHITE HOUSE SPOKESWOMAN
"It's a sober moment, and one that all of us can focus on in terms of the number of 4,000.
"The president feels each and every one of the deaths very strongly and he grieves for their families ... He obviously is grieved by the moment but he mourns the loss of every single life.
"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 ... He wants them to know that their sacrifices will not be in vain."
BRYAN WHITMAN, PENTAGON SPOKESMAN
"Every single loss of a soldier, sailor, airman and Marine is keenly felt by us in the (Defense) Department, by military commanders, by families, friends.
"In late March of 2008 ... both coalition and Iraqi security force casualties are down significantly from about May of '07. 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."
ILLINOIS SEN. BARACK OBAMA, DEMOCRATIC PRESIDENTIAL CANDIDATE
"It is with great sadness that we have reached another grim milestone in Iraq, with at least 4,000 of our finest Americans having been killed.
"It is past time to end this war that should never have been waged by bringing our troops home, and finally pushing Iraq's leaders to take responsibility for their future. As we do (this), we must serve the memory of all who have died as well as they served our country, by providing support for their families, caring for our troops and veterans, and upholding the American values which our fallen heroes exemplified."
NEW YORK SEN. HILLARY CLINTON, DEMOCRATIC PRESIDENTIAL CANDIDATE
"Five years after the start of the war there have now been 4,000 U.S. military deaths in Iraq. Tens of thousands of our brave men and women have also suffered serious wounds, both visible and invisible, to their bodies, their minds and their hearts.
"As president, I intend to honor their extraordinary service and the sacrifice of them and their families by ending this war and bringing them home as quickly and responsibly as possible."
REP. NANCY PELOSI, CALIFORNIA DEMOCRAT AND SPEAKER OF THE U.S. HOUSE OF REPRESENTATIVES
"Today, we mourn America's fallen heroes; the deaths of 4,000 American soldiers is a grim reminder of the enormous cost of war in Iraq: the human cost.
"With 4,000 American lives lost and thousands injured, many of them permanently, Americans are asking how much longer must our troops continue to sacrifice.
"Americans also understand that the cost of the war to our national security, military readiness and our reputation around the world is immense and that the threat to our economy ... is unacceptable." (Compiled by David Morgan in Washington, edited by Todd Eastham)