The announcement of the troop tour extensions came during the bloodiest month of the Iraq war to date. More than 130 American soldiers and Marines died in combat in April 2004, mostly from clashes in the Sunni stronghold of Fallujah and from Shiite militia uprisings in southern Iraqi cities.

The total for April surpassed the 109 killed between the start of the war on March 19, 2003, and the day President Bush declared the end to major combat on May 1 of that year. Department of Defense figures show as of May 18, 2004, a total of 576 U.S. soldiers have been killed in action in Iraq.

Fighting intensified following the March ambush of the SUVs carrying four contract workers for the coalition in Fallujah, a Sunni Triangle city about 35 miles west of Baghdad.

An angry mob beat and dragged the bodies through the town, eventually hanging them from a bridge over the Euphrates River, chanting, "Fallujah is the graveyard of Americans."

The next day, U.S. military officials vowed to "pacify" Fallujah and hunt down those responsible for killing and mutilating the workers.

In early April, as hundreds of U.S. and Iraqi troops took positions around Fallujah in preparation for what would be a bloody series of clashes with suspected Saddam loyalists and other insurgents, radical Shiite cleric Muqtada al-Sadr was urging opposition to the U.S.-led occupying forces in Shia-populated areas in the south.

Battles raged and continue to flare between coalition troops and militants, including members of al-Sadr's al-Mahdi Army, in the southern holy cities of Karbala, Najaf and Nasiriyah.

Hundreds of insurgents and Iraqi civilians have been killed as a result of the fighting, but there is no official tally.

On May 16, 2004, Secretary of State Colin Powell reiterated on NBC's Meet the Press that U.S. troops would remain in Iraq beyond the June 30 transfer of sovereignty to an interim Iraqi government.

"They (Iraqis) need our financial support, they need the reconstruction effort that is under way, and frankly they need the U.S. armed forces and other coalition forces that are present to help create and environment of security and stability," he said.

Troop strength has decreased significantly from the Cold War era to the present as the Army reoriented itself from the threat of the Soviet bloc to the peacekeeping missions of the 1990s, said Blair Haworth of the U.S. Army Center of Military History.

According to the Army's 2001 Posture Statement, the present-day Army "is one-third smaller, deploys more frequently, and is more likely to conduct stability and support operations than its Cold War predecessor."

But while overall troop strength decreased, "there became an enormous number of commitments," Haworth said.

The use of reserves and the extended tours in Iraq reflect the demands on U.S. forces. In addition to Iraq, the United States has a military presence in places such as South Korea, the Balkans and Afghanistan.

More than 198,000 soldiers are deployed and stationed in 120 countries around the world, according to the Army's 2003 Posture Statement. More than 110,000 soldiers in the reserves are involved in operations in locations including Afghanistan, Philippines, Pakistan, Kuwait, Persian Gulf, and Guantanamo Bay, Cuba, in response to the Sept. 11, 2001, terrorist attacks, the report says.

The Army says it is working on adjusting its mission as traditional warfare gives way to unpredictable acts of terrorism.

-- By Larisa Epatko, Online NewsHour