Direct proof of use
U.S. Navy P-3C Orion patrol aircraft were used by coalition forces in the 1990 Gulf War for maritime surveillance, interdiction support, and targeting support. Patrol and Reconnaissance Wing 11's command history says the P-3C proved itself as a multi-mission platform over land and sea while supporting Operations Desert Shield and Desert Storm.
A contemporary U.S. Naval Institute account by VP-19 officers describes P-3 maritime patrol aircraft as immediately in demand after Iraq's invasion of Kuwait and states that patrol aircraft flew more than 7,500 hours supporting battle groups during the seven-month operation. The same account records 3,170 hours in direct support of Operation Desert Storm and 219 missions supporting 31 naval engagements that damaged or destroyed 53 Iraqi naval targets.
Sources: Patrol and Reconnaissance Wing 11 Command History, USNI If It Was There P-3s Found It
Timeline
P-3s were among the early U.S. military assets to arrive after the August 2, 1990 Iraqi invasion, and they began surveillance supporting maritime-interdiction operations during Desert Shield. By January 1991, dedicated Arabian Gulf sorties, British Nimrod augmentation, and inverse synthetic aperture radar-equipped P-3s supported round-the-clock coverage in the North Arabian Gulf.
When Desert Storm began on January 17, 1991, an Outlaw Hunter-configured P-3 detected an Iraqi patrol boat and vectored carrier strike aircraft for the first reported naval kill of the war. On February 7, 1991, an NHHC reserve patrol-squadron appendix records a reserve crew flying a VP-46 ISAR-equipped P-3C Update III Orion locating two Iraqi gunboats and vectoring an A-6 aircraft that attacked and sank them.
Sources: USNI If It Was There P-3s Found It, NHHC Reserve Patrol Squadron Call-Ups
Role in the conflict
The P-3C's Gulf War role centered on surveillance and targeting rather than direct weapons release. USNI's Desert Storm account says P-3s provided surface-contact identification, targeting to strike aircraft, communications relay, electronic surveillance, mine detection, and battle-damage assessment. It also states that P-3 weapons were not employed during the campaign.
Outlaw Hunter was the most specific P-3C configuration documented in the sources. A Naval Aviation News article describes it as a P-3C proof-of-concept aircraft with over-the-horizon targeting equipment that combined inverse synthetic aperture radar, GPS, satellite communications, and a tactical workstation to classify and pass target data. The article says the aircraft was taken to the Persian Gulf War by VP-19 and flown throughout the conflict.
The documented user was the U.S. Navy on the coalition side. The sources support fielding and combat use as a maritime patrol, surveillance, interdiction-support, mine-detection, and targeting platform; they do not support a claim that P-3C aircraft fired their own weapons during Desert Storm.
Sources: USNI If It Was There P-3s Found It, Naval Aviation News Outlaw Hunter, Outlaw Hunter Article Mirror