FACTBOX - U.S. leaders mark 4,000 American dead in Iraq

(Reuters) - 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.

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