MARINE CORPS BASE HAWAII — The biennial Rim of the Pacific exercise usually has a certain cadence to its scenario: a hurricane blows through an already tense island chain, but humanitarian relief efforts are hampered by adversarial attacks.

Then missiles begin to fly, and amphibious ships push ground forces ashore to take the beach and quell the violence, winning the day and ending the drill.

But this year’s RIMPAC flipped that storyline on its head. Brig. Gen. Joseph Clearfield, the deputy commander of U.S. Marine Corps Forces Pacific and the commander of Fleet Marine Forces in the exercise, told Defense News that ground troops were already ashore, looking toward the seas and contributing to the maritime fight.

RIMPAC “always kind of built to this great, big allied and partnered amphibious assault. Well, this year … there are forces that are already ashore in a permissive environment when the scenario goes into hostilities kickoff, and they stay ashore, and they’re with partner nations ashore,” he said.

The exercise then lets those ground forces explore how to contribute to maritime dominance, he added, including sea denial and aerial denial.

This mirrors what the Corps is trying to accomplish in the Pacific region to counter China’s growing influence and military activities.

The service, through its new stand-in forces and its expeditionary advanced base operations concepts, envisions small groups of Marines scattered throughout regional islands and shorelines, including the Philippines, Indonesia, Japan and anywhere else partner nations allow. Those small units will carry everything they need to move from one place to another while conducting surveillance missions, establishing refueling spots for joint forces and launching missiles.

Key to the concept is mobility, interoperability and focusing on maritime missions — all demonstrated during RIMPAC 2022, which runs June 29-Aug. 4.

The Marine Corps and U.S. Army units specializing in the High Mobility Artillery Rocket System were ashore and ready to shoot at maritime targets, Clearfield said in the interview. The new 3rd Marine Littoral Regiment based in Hawaii and the California-based 7th Marine Regiment set up expeditionary advanced bases ashore to provide sensing services for the coalition force and prosecute targets if the opportunity arose.

For 7th Marines, it did.

F/A-18 Hornet jets from Marine Fighter Attack Squadron 232, operating with 7th Marines as part of the temporary Marine Air-Ground Task Force 7, shot modified Joint Direct Attack Munition bombs against the decommissioned amphibious ship Denver during a sinking exercise.

Marine Corps Forces Pacific spokesman Maj. Nick Mannweiler told Defense News this was the first employment of this JDAM weapon by Marine aircraft, and its first use against a ship. The Air Force previously tested the modified JDAM against a full-scale vessel target, but not an actual warship.

Additionally, the squadron, which also fired high-speed anti-radiation missiles and a Harpoon anti-ship missile, practiced the sensing and targeting portion of the kill chain alongside Navy P-8 maritime patrol aircraft and Air Force MQ-9 Reaper drones. According to a news release on the sinking exercise, dubbed SINKEX, this demonstrated “the U.S. Marine Corps’ ability to integrate into a joint and combined command and control network anywhere.”

Clearfield said this followed recent demonstrations of ways the Corps can sink ships from the air and the ground, as the service pivots to being an ashore node in the maritime fight.

At last summer’s Large Scale Exercise, the Corps demonstrated NMESIS — the Navy Marine Expeditionary Ship Interdiction System — an unmanned Joint Light Tactical Vehicle affixed with a Naval Strike Missile launcher. NMESIS was one of several naval systems to fire at the decommissioned frigate Ingraham off Hawaii during SINKEX.

RIMPAC 2022 featured the JDAM and the Harpoon to sink the ex-Denver.

RIMPAC planners had intended for Marine Light Attack Helicopter Squadron 169 to fire a Joint Air-to-Ground Missile, which would have been the first time Marines fired this weapon during a training event. (Mannweiler noted the service first tested the JAGM against maritime targets with AH-1Z helos in December 2021.)

But the event was ultimately scrapped “due to range-timing challenges in the course of conducting the multi-service operation. This decision was made in the interests of range safety due to these timing challenges.” But, he added, “sinking exercises are highly valuable training opportunities — a hallmark of RIMPAC — and the Marine Corps will seek out future opportunities to train and exercise with JAGM at sea.”

Though the military didn’t demonstrate JAGM at RIMPAC, Marines now have at least four proven tools in their inventory to sink a ship from ashore.

“You can see here where, from the Large Scale Exercise [in] August ′21 to the SINKEX in RIMPAC ′22, we’re going to demonstrate the ability to gain and maintain custody [of maritime targets] both from ashore and in the air, and putting together lethality from ashore and lethality from our aviation combat element,” Clearfield said.

The general praised his chain of command — Marine Forces Pacific, U.S. Pacific Fleet and U.S. Indo-Pacific Command — because “every exercise we do, they want a list enumerated of what are we doing: what experiments, what first-ofs are we doing, or what second-ofs or third-ofs. It’s just become a huge part of our DNA right now that we take advantage of all these things to try something — either something that we’ve got in theory, or something doctrinally that should work, but actually exercising it.”

Megan Eckstein is the naval warfare reporter at Defense News. She has covered military news since 2009, with a focus on U.S. Navy and Marine Corps operations, acquisition programs, and budgets. She has reported from four geographic fleets and is happiest when she’s filing stories from a ship. Megan is a University of Maryland alumna.

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