Vietnam War Combat operations The 31st Marine Expeditionary Unit was commissioned on 1 March 1967, as
Special Landing Force Alpha, for operations in
Vietnam. The unit made the first of many amphibious deployments from
Okinawa to the coast of Vietnam on 10 April 1967. The first operation conducted was on 14 April 1967, when the MEU conducted a rescue of the crew of the SS Silver Peak, a Panamanian vessel run aground by Typhoon Violet, in vicinity of Minami Ko Shima Island, Japan. Days later, SLF Alpha was committed to
Operation Union, a search and destroy mission in Vietnam. It was during this period of intense combat that SLF Alpha earned the
Presidential Unit Citation. The unit participated in continuing combat operations ashore over the next three years, including the Vietnam Tet counteroffensive in 1969, while returning to Okinawa periodically for re-outfitting and the rotation of forces. Special Landing Force Alpha was officially designated as the 31st Marine Amphibious Unit (MAU) on 24 November 1970. Once more the unit returned to the
Gulf of Tonkin. This time the 31st MAU was not committed to overt land operations, as the Vietnam War was winding down. The 31st MAU performed presence missions and conducted a series of special operations to May 1971. From June 1971 until April 1975, the 31st MAU conducted many deployments to the waters off Vietnam.
Operation Eagle Pull On 6 January 1975,
Commander in Chief Pacific Command (CINCPAC) placed the 31st MAU on 96-hour alert to move the evacuation fleet into the Gulf of Thailand for the possible implementation of
Operation Eagle Pull, the evacuation of the United States Embassy in
Phnom Penh,
Cambodia. On the afternoon of 11 April 1975, the 31st MAU received orders to execute Operation Eagle Pull. At 06:00 on 12 April 12 x CH-53s of
HMH-462 launched from the deck of the
USS Okinawa and moved a security force of 360 Marines ashore. The majority of the evacuation proceeded smoothly with HMH-462 transporting 84 US nationals and 205 Cambodians and third country nationals. By 10:41 all the evacuees, including Ambassador
John Gunther Dean and
President Saukham Khoy had been extracted. Helicopters of HMH-463, operating from the
USS Hancock, began to land to extract the ground security force. Beginning at approximately 10:50, 107 mm rocket and 82 mm mortar fire began impacting in the vicinity of LZ Hotel. At 10:59, the last element of
2nd Battalion, 4th Marines left the zone. The last Marine helicopter landed on USS
Okinawa at 12:15. On 13 April, the evacuees were flown to
U-Tapao Air Base in
Thailand. Amphibious Ready Group Alpha proceeded to the South China Sea to rendezvous with
Task Force 76 as it stood by to implement
Operation Frequent Wind, the evacuation of
Saigon.
Operation Frequent Wind After departing the Gulf of Thailand, the 31st MAU was attached to the
9th Marine Amphibious Brigade in support of
Operation Frequent Wind, the final evacuation of
Saigon as
North Vietnamese forces entered the city.
1980s and 1990s The 31st MAU at this time was established as the only permanently forward-deployed U.S. presence in the
Western Pacific, Southern Pacific, and Indian Ocean with Special Operations capabilities. In February 1980, the
USS Okinawa (LPH-3) task force, already with Marine Cobra gunships and Harrier attack aircraft from California, made port at
Pearl Harbor to take aboard the final elements of the MEU, which consisted of
3rd Battalion, 3rd Marines (3/3), helicopters from
MAG-24,
Force Recon, and
Marine Amphibious Unit Service Support Group 31 (MSSG-31) in support, all out of Kaneohe Bay's 1st Marine Brigade. On 24 April, this group in support of 3/3 Marines rendezvoused with
USS Nimitz off the coast of
Iran, as a reserve in the ill-fated
Operation Eagle Claw, the failed attempt to rescue of the
53 American captives at the
Embassy of the United States, Tehran. Combat operations were replaced by regional exercises, which allowed training opportunities in a variety of countries. During the late 1970s and early 1980s, the 31st MEU engaged in humanitarian operations, for example, the 1984 floods in Bangladesh. In 1983, the 31st MEU was recalled from a combined exercise with local forces in
Kenya and positioned in the
Mediterranean Sea. From September to October 1983, its mission was to support the
Multinational U.S. peacekeeping forces in
Beirut, during an intense period of complex political and life-threatening conditions in
Lebanon. They took over the command operations after their sister unit, the
24th MEU, was
attacked in the Beirut bombing. It was the 31st MEU's last military operation of that period. In May 1985, the unit was deactivated on ship, off the shore of San Diego. During this time the 31st MEU was based at the Marine Barracks, Subic Bay Naval Station. On 9 September 1992, the unit was redesignated as the 31st Marine Expeditionary Unit (
Special Operations Capable). In 1994, the unit was relocated to its current home station at
Camp Hansen, in
Okinawa, Japan.
Iraq 1998-99 In November 1998,
Saddam Hussein’s regime was failing to comply with
United Nations resolutions, and interfering with weapons inspectors looking for weapons of mass destruction. As the crisis came to a head, the 31st MEU was recalled back to Okinawa. At the time, most of the MEU's Marines were on
Guam conducting urban warfare training, and a new infantry battalion had just arrived from CONUS. All Marines and equipment were loaded by 11 November, at which time the ships set sail for the
Persian Gulf. From November 1998 to February 1999, the 31st MEU sailed off the coast of
Kuwait, participating in
Operation Southern Watch and
Operation Desert Fox.
East Timor The 31st MEU, in concert with Amphibious Squadron Eleven (Phibron 11), deployed to support
Australian Defence Force (ADF) operations in
East Timor from 30 September 1999, to 26 October 1999. Flying from the
USS Belleau Wood (LHA-3), the MEU conducted "lily pad" operations around East Timor, providing security, logistics, and communications support for the
International Force East Timor (INTERFET) led by Major General
Peter Cosgrove from the
Australian Army. The Marines distributed more than 500 tons of food, water, and supplies around East Timor during this time. In January 2000, a
Special Purpose Marine Air-Ground Task Force consisting of Golf Company,
2nd Battalion, 5th Marines, Charlie Company
1st Battalion 5th Marines, then the MEU's Battalion Landing Team; portions of the Command Element;
HMM-265, and
MSSG-31 deployed to
East Timor aboard the . In East Timor, the Marines and Sailors supported the transition from the Australian-led INTERFET to the new
United Nations Transitional Administration East Timor (UNTAET).
9-11 Late in the evening of 11 September 2001, all US Forces were secured to their quarters as
Super Typhoon Nari was passing over Okinawa. After the
September 11 attacks, the MEU received a 96-hour warning order for deployment and was notified that naval shipping was en route to embark them soonest. Marines prepared to deploy and began staging equipment as the storm continued. The helicopter squadron was the last to board due to the passing storm, and the on-load was successfully completed in 93 hours. The MEU immediately steamed south towards its expected destination,
Afghanistan. As the ships passed
Singapore, the MEU was re-tasked to support UNTAET operations in East Timor. The
15th Marine Expeditionary Unit, returning from a deployment to East Timor, was assigned the task of supporting combat operations in Afghanistan.
21st century From September 2004 to March 2005, the 31st MEU, including Battalion Landing Team
1st Battalion 3rd Marines with attached Charlie Battery of
1st Battalion 12th Marines, conducted combat actions during the
Iraq War. Participation included a major role in
Operation Phantom Fury, the clearing of
Fallujah in November 2004. With organizational changes to Marine Corps' reconnaissance units in 2006, all the MEU's
Special Operations Capable (SOC) designations were removed. The 31st MEU then became titled as a Maritime Contingency Force, although it remains capable of conducting the same wide variety of specialized missions on both sea and land. In February 2006, the 31st MEU was sent to the Philippines to provide relief assistance during the
mudslides in southern Leyte. On 21 September 2007, the 31st MEU Command Element dedicated its headquarters building at Camp Hansen, Okinawa to Sergeant
Rafael Peralta, who died in
Iraq during
Operation Phantom Fury, while assigned to the 31st MEU BLT 1/3 Alpha Company 1st Platoon. Sgt Peralta received the
Navy Cross for his actions in Fallujah. From 13 May to 5 June 2008, Marines of the 31st MEU sailing aboard the 's
expeditionary strike group waited off the coast of
Burma prepared to provide relief as part of
Operation Caring Response following
Cyclone Nargis. US leaders sent the strike group home in early June after failing to gain permission for them to come ashore from the Burmese government. In October 2009, the MEU assisted in humanitarian & disaster relief in Luzon, Philippines after Typhoons
Ketsana and
Parma hit back to back. Simultaneously, elements of the MEU assisted in Sumatra, Indonesia after
earthquakes struck the region. In October 2010, the 31st MEU conducted humanitarian assistance and disaster relief operations in northern Luzon after
Super Typhoon Megi hit the Philippines.
Operation Tomodachi, Japan - 2011 The 31st MEU was split into three separate parts on 11 March 2011, the day of the 9.0
earthquake and tsunami. The largest ship, , with most of the Marines and Sailors of the 31st MEU aboard, had just completed an exercise in Cambodia and had arrived in Malaysia for a port visit. When the 31st MEU leadership received news of the tsunami, they initiated an immediate recall of all personnel who were away from the ship on liberty. The ship quickly took on some supplies, and in less than 24 hours was underway to Japan where it would meet up with and . Germantown and Harpers Ferry were both in Indonesia with elements of the 31st MEU embarked. Marines and sailors aboard the USS Harpers Ferry were scheduled to participate in a large humanitarian assistance and disaster relief exercise starting 12 March. Both ships were immediately alerted upon news of the disaster in Japan and headed north for the stricken country in support of what would become
Operation Tomodachi. On 17 March, the Essex Amphibious Ready Group and the 31st MEU arrived off the coast of Akita, Japan, and began flying coastal surveillance flights in the initial stages of
Operation Tomodachi. On 22 March, the ARG repositioned off the east coast of Japan, near Hachinohe, and the 31st MEU immediately began delivering relief supplies ashore via helicopters of Marine Medium Helicopter Squadron 262 (Reinforced). Supplies delivered included water, blankets, and other health and comfort items. HMM-262 (REIN) conducted a total of 15 survey missions and 204 supply delivery missions, with nearly 300 hours of flight time. On 27 March, the MEU and Essex ARG's priority became support to the isolated island of Oshima as part of
Operation Tomodachi. Elements of the 31st MEU, including
Marine Medium Helicopter Squadron 262 (Reinforced),
Combat Logistics Battalion 31,
2nd Battalion 5th Marines and the command element went ashore on Oshima Island to remove debris, deliver critical supplies to the isolated area, and provide life support.
Combat Logistics Battalion 31 began by transporting relief supplies, which included moving commercial electric utility vehicles, a fuel truck, a water re-supply vehicle and civilian workers from the Tohoku Power Company by U.S. Navy landing craft, to attempt to restore partial power to the cut-off island. The same day the utility vehicles were delivered, the island received power for the first time since the disaster. During the Oshima operation, pallets of clothes, blankets, and food were flown to the JMSDF helicopter destroyer JS Hyuga (DDH 181) by Marine helicopters, where they were distributed to displaced residents of the island who were temporarily embarked aboard the ship. Working alongside the JGSDF, the 31st MEU delivered 15,000 pounds of supplies to the island and cleared tons of debris from harbors, roads and beaches. Marines created temporary shower facilities allowing residents to bathe. For some, it was the first time they had been able to take a shower since the tsunami struck. In total, the 31st MEU and the Essex ARG moved 164,000 pounds of relief supplies to those affected by the disaster, including five cities, Oshima Island and the Japanese ship.
Typhoon Haiyan and Operation Damayan - 2013 In November 2013, the 31st MEU acted as a contingency reserve in wake of
Typhoon Haiyan in the Republic of the Philippines. The MEU was conducting unit turnover when they were tasked to respond and quickly embarked aboard the USS Ashland (LSD 48) and USS Germantown (LSD 42) of Amphibious Squadron 11 to assist in disaster relief operations in conjunction with the U.S. Department of State and Joint Task Force 505. The Aviation Combat Element of the 31st MEU, Marine Medium Tiltrotor Squadron 265, flew over 415 flight hours to deliver aid supplies throughout the region. The rest of the MEU remained at sea in the Leyete Gulf of the Philippines to act as a contingency reserve in the event any more assistance was needed, or another disaster were to strike the area.
South Korean ferry Sewol - 2014 In April 2014, the 31st MEU on board the
USS Bonhomme Richard assisted in air-sea search and rescue operations of the Korean ferry
Sewol that "sank near the island of Jindo off the southwestern coast of the Republic of Korea 16 April". that sank 16 April 2014
Typhoon Soudelor, Saipan - 2015 From 2–3 August 2015,
Typhoon Soudelor devastated the island of Saipan in the Commonwealth of Northern Mariana Islands. Approximately 600 Marines and sailors of the 31st MEU responded to assist local and federal agencies with disaster relief efforts. Over two weeks, the 31st MEU delivered more than 19,000 gallons of water and 47,000 individual meals provided by the
Federal Emergency Management Agency to five distribution sites across the island. The Marines distributed an additional 366,000 gallons of potable water to the people of Saipan, 279,000 gallons of which were purified using a Lightweight Water Purification System and a Tactical Water Purification System. The 31st MEU also distributed more than 10,000 pounds of emergency supplies provided by the
Red Cross.
Operation Chinzei, Japan - 2016 From 15–17 April 2016,
a series of earthquakes struck the Japanese prefecture of Kumamoto, causing 48 deaths and displacing some 100,000 people. At the request of the Government of Japan, approximately 130 Marines and Sailors of the 31st MEU provided support to operations conducted by Joint Task Force Chinzei, led by the
Japan Self-Defense Force. From 18–23 April, 31st MEU MV-22B Ospreys operating out of
Marine Corps Air Station Iwakuni, Japan, delivered more than 82,000 pounds of food, water, blankets, toiletries and other items to be distributed to earthquake victims.
Defense Support of Civil Authorities, Commonwealth of the Northern Mariana Islands, September–November 2018 , Okinawa, 26 September 2025 During Fall Patrol 2018, the 31st MEU and CLB-31 provided assistance to the people of the
Commonwealth of the Northern Mariana Islands (CNMI), a U.S. territory, after two devastating typhoons. On 10 September, Super
Typhoon Mangkhut swept across CNMI, causing widespread damage to the islands of Rota and Saipan. The Marines and sailors of the 31st MEU and CLB-31, embarked aboard the and
USS Ashland (LSD-48), began providing assistance to CNMI officials and the
Federal Emergency Management Agency (FEMA) as soon as the skies cleared over CNMI. During Mangkhut relief efforts, the 31st MEU and CLB-31, partnering with
Amphibious Squadron 11, cleared roads and flew 63 air missions to deliver assistance personnel and more than 29,000 pounds of cargo for the people of CNMI. Mangkhut relief efforts ended on 14 September, when the 31st MEU and CLB-31 re-embarked aboard the Wasp and Ashland to continue deployment. Just over a month later, on 25 October, the second-strongest storm ever to hit U.S. soil, Super
Typhoon Yutu, made a direct hit on the islands of Tinian and Saipan. The 31st MEU and CLB-31, which had just returned to Okinawa after completing deployment, received orders to assist relief efforts just days after returning to Camp Hansen. The 31st MEU arrived on 29 October, establishing ashore at
Tinian International Airport. A more robust follow-on force arrived aboard the USS Ashland on 3 November, aiding with water purification, route clearance, damage assessments and restoration of municipal utilities. All told, the 31st MEU and CLB-31, which led the multiservice response effort on Tinian, cleared miles of roadway, purified more than 20,000 gallons of drinking water, and helped deliver and assemble more than 150 FEMA-provided shelters, handing control of the DSCA effort to the U.S. Navy
Seabees of
Naval Mobile Construction Battalion 1 on 14 November.
Guam and Papua New Guinea - 2023-2024 In May 2023, the 31st MEU responded to Typhoon Mawar, which struck Guam as a Category 4 storm. Marines assisted with defense support of civilian authorities (DSCA) and base restoration, clearing debris across Naval Base Guam, Marine Corps Camp Blaz, and Anderson Air Force Base. Later that year in August 2023, the unit conducted humanitarian assistance and disaster relief (HADR) operations on Bougainville Island, Papua New Guinea, following volcanic activity.
Japan and Philippine Sea - 2025-2026 in Okinawa, Japan, 30 November 2025 In late 2025, the MEU transitioned its primary aviation operations from the USS America (LHA-6) to the USS Tripoli (LHA-7). This shift allowed the unit to execute advanced Expeditionary Advanced Base Operations (EABO), including a rapid power projection drill in which roughly 400 Marines were transported 1,100 miles from Okinawa to Camp Fuji in under 36 hours. To conclude the year, the MEU integrated with the USS George Washington (CVN-73) to support anti-submarine warfare operations in the Phillippine Sea using MV-22B Ospreys. From February to March 2026, the 31st MEU, along with the 3rd Marine Expeditionary Brigade, trained alongside the Japan Ground Self-Defense Force’s (JGSDF) Amphibious Rapid Deployment Brigade and 3rd Amphibious Rapid Deployment Regiment for Exercise Iron Fist 26. This 20th bilateral iteration supported interoperability through complex training, including ship-to-shore movements aboard the USS Tripoli (LHA-7), field exercises, simulated amphibious assaults, close air support, and urban operations. The training featured comprehensive air, ground, and sea exercises, including an amphibious landing on Tanegashima island.
2026 Iran war On 13 March 2026, during the
2026 Iran war, elements of the 31st MEU aboard
USS Tripoli were reportedly ordered to deploy to the
U.S. Central Command area of responsibility in the Middle East. They are expected to try to secure the
Strait of Hormuz amid the
2026 Strait of Hormuz crisis. On 19 April 2026, President Trump announced that the US had attacked the Iran-flagged cargo ship
TOUSKA after it attempted to breach the
US naval blockade of Iran, blowing a hole in its engine room and taking the ship into custody. The vessel, almost long, was en route to
Bandar Abbas. It was warned by the guided missile destroyer over a six hour period before the destroyer fired several rounds from its
5-inch/54-caliber Mark 45 gun into the engine room, disabling it. It was then seized by the 31st MEU in the Gulf of Oman. Iran described the seizure as a
US-Iran truce violation. Iran retaliated against the seizure by launching attack drones at U.S. ships, although no damage was reported. According to
Reuters, the seized ship was probably carrying equipment that the US considered "dual-use," meaning that it had equipment that could be used by the Iranian army. ==31st MEU commanding officers==