Direct proof of use
M270 MLRS use in the 2003 Iraq War is directly documented through reported U.S. Army rocket expenditure and an Army professional military education paper by an MLRS battalion intelligence sergeant who served in Operation Iraqi Freedom I. Human Rights Watch, citing U.S. ground-force and field-artillery reporting, stated that the 3rd Infantry Division, 101st Airborne Division, and 214th Field Artillery Brigade reported using 1,014 MLRS rockets in Iraq.
The Army Sergeants Major Academy paper describes the 2003 attack toward Baghdad with MLRS launchers planned for moving fire missions, then records a final-protective-fires mission and subsequent MLRS calls for fire against targets including some in Baghdad. Those sources support U.S. use of the launcher in combat, not merely deployment or possession.
Sources: Human Rights Watch Off Target, MLRS From Desert Storm to Iraqi Freedom
Timeline
The initial major-combat phase of Operation Iraqi Freedom ran from March to May 2003. During that phase, U.S. Army formations used MLRS rockets and ATACMS missiles as part of ground operations against Iraqi forces.
Human Rights Watch's December 2003 report gave a public aggregate figure for MLRS rocket use by listed U.S. Army formations. The Army Fires Center command history later recorded Operation Iraqi Freedom as part of the background for M270A1 and MLRS-family precision fires, including the 2004 urgent operational need that accelerated Guided Unitary MLRS after commanders sought an all-weather precision MLRS munition for urban joint fires in Iraq.
Sources: U.S. Army CMH Operation Iraqi Freedom, Human Rights Watch Off Target, Annual Command History 2008
Narrative
In the 2003 Iraq War, the M270 MLRS served on the United States and coalition side as tracked rocket artillery for long-range fire support, interdiction, counter-battery fire, and suppression missions. Human Rights Watch described U.S. ground-launched cluster munitions as being used primarily for counter-battery fire against Iraqi mortars and artillery, with MLRS cluster munitions used for longer-range targets and ground-launched clusters also used in suppression of enemy air defense missions.
The 2003 evidence includes both expenditure reporting and operational narrative. Human Rights Watch reported 1,014 MLRS rockets used by the 3rd Infantry Division, 101st Airborne Division, and 214th Field Artillery Brigade, while the Army paper describes MLRS fire support becoming more requested by maneuver commanders after an early final-protective-fires mission during the move on Baghdad.
The sources also show why later Iraq use changed. The Army Fires Center history records that an urgent 2004 request from the Multi-National Forces commander in Operation Iraqi Freedom sought a precision, all-weather, high-explosive MLRS munition for urban joint fires; Guided Unitary MLRS rockets were then accelerated and delivered in 2005. That later development is relevant background for the M270 family in Iraq, but the direct 2003 claim here rests on reported MLRS rocket firing and the 2003 operational account.
Sources: Human Rights Watch Off Target, MLRS From Desert Storm to Iraqi Freedom, Annual Command History 2008