Direct proof of use
The Sea King was used by United States and coalition forces in the 2003 Iraq War through Royal Navy Commando Helicopter Force operations. Royal Navy history records 846 Naval Air Squadron taking part in the assault on the al-Faw peninsula before deploying to Basra for Operation Telic and remaining in Iraq until 2007.
Royal Navy history for 845 Naval Air Squadron separately records the squadron returning to the Gulf in 2003 to remove Saddam Hussein's regime and says its Sea Kings remained in Iraq after the regime was toppled. A Crown-copyright Royal Navy image record from Basra states that Sea King Mk4s of 845 and 846 Naval Air Squadrons carried out multiple jobs during tours at Basra International Airport, including perimeter checks, personnel moves, and medical-air-ambulance availability.
Sources: 846 Naval Air Squadron, 845 Naval Air Squadron, Wikimedia Basra Sea King Image
Timeline
The clearest dated milestone is the opening al-Faw operation. The Royal Navy's 2023 retrospective describes the 3 Commando Brigade assault that began on the night of March 20-21, 2003, from land bases in Kuwait and from HMS Ark Royal and HMS Ocean in the northern Gulf. The 846 NAS history connects the squadron to that al-Faw assault and later Basra deployment.
By April 2006, Royal Navy image metadata placed Sea King Mk4 helicopters from 845 and 846 NAS at Basra International Airport during southern Iraq operations. The same metadata describes the aircraft moving passengers to other parts of southern Iraq and supporting perimeter, personnel-transport, and medical-air-ambulance tasks.
Sources: Royal Navy Al-Faw Retrospective, 846 Naval Air Squadron, Wikimedia Basra Sea King Image
Narrative
In Iraq, the Sea King Mk4 was a British-operated coalition support helicopter rather than an Iraqi platform or a strike aircraft. Its documented users were Royal Navy Commando Helicopter Force squadrons, especially 845 and 846 Naval Air Squadrons, working with Royal Marines and other coalition forces during Operation Telic.
The aircraft's role began with amphibious and air-assault support for the al-Faw campaign and continued into southern Iraq support activity around Basra. A Ministry of Defence interview with a Commando Helicopter Force officer describes the 2003 planning for the al-Faw assault, including aviation advice for 40 Commando Royal Marines, followed by supporting and reinforcing work in Iraq with Navy Sea Kings, RAF Chinooks, and U.S. Air Force helicopters.
Institutional image and museum records show the post-invasion support role in practical terms. The Wikimedia Royal Navy image record describes Sea King Mk4s moving personnel, checking the Basra Airport perimeter, and standing available as a medical air ambulance. An Imperial War Museums Operation Telic record describes British troops waiting for a Royal Navy Sea King near Basra before being flown to remote roads for temporary vehicle checkpoints intended to deter terrorism and weapons smuggling.
Sources: 845 Naval Air Squadron, 846 Naval Air Squadron, Defence Focus Jim Cobbett Interview, Wikimedia Basra Sea King Image, IWM Operation Telic Sea King