BAGHDAD -- A roadside bomb killed three American soldiers north of Baghdad on Saturday, pushing the U.S. death toll in the five-year conflict to nearly 4,000.

The latest deaths brought to 3,996 the number of U.S. service members and Pentagon civilians who have died since the war began on March 20, 2003, according to an Associated Press count.

With the war entering its sixth year, President Bush paid tribute Saturday to America's fallen service members, saying in his weekly radio address that they will "live on in the memory of the nation they helped defend."

Speaking for the Democrats, however, Sen. Robert Menendez of New Jersey called on Bush to "face the reality" in Iraq and "tell us the truth" about the cost of the conflict as America is struggling with a faltering economy and mounting casualty tolls.

U.S. officials have pointed to a number of positive signs, including a 60% drop in violence since Bush ordered 30,000 U.S. reinforcements to Iraq early last year. Iraqis have also made some limited progress in power-sharing deals among rival Shiite, Sunni and Kurdish communities.

However, U.S. military commanders have been careful to point out that security gains are fragile and that major violence could erupt abruptly.

Much of the progress has been due to a move by thousands of Sunnis to abandon the insurgency and join pro-U.S. defense groups -- known as "awakening councils." Another was a cease-fire called last August by firebrand Shiite cleric Muqtada al-Sadr, leader of the feared Mahdi Army militia.

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