YOKOTA AIR BASE, Japan — America’s allies in the Pacific are building their own amphibious forces and training them to fight alongside American troops even as the U.S. Marine Corps prepares to cut thousands of Marines from its rolls.

As the Afghan war winds down, tightening U.S. defense budgets call for the Corps to trim from 190,000 to 182,000 personnel, and the number could go even lower — to 175,000 — if sequestration-level cuts are reimposed. The fiscal problems have cast doubt on the Pacific Pivot that the U.S. has been pursuing since 2011.

Just last week, Adm. Samuel Locklear III —commander of U.S. Pacific Command — told the Senate Armed Services Committee that the Navy and Marines do not have enough assets to carry out a contested amphibious operation in the Pacific if a crisis arises.

“We have had a good return of our Marines back to the Asia-Pacific, particularly as the activities in the Middle East wind down in Afghanistan … But the reality is, that to get Marines around effectively, they require all types of lift,” he told the committee during the March 25 hearing. “They require the big amphibious ships, but they also require connectors (meaning landing craft landing craft and other amphibious vehicles). The lift is the enabler that makes that happen, so we wouldn’t be able to [successfully carry out a contested amphibious assault without additional resources].”

It appears that two of the U.S. military’s staunchest Pacific partners — Japan and Australia — are ready to pick up some of the slack.

Australia recently ordered one of its army battalions to begin amphibious training, while Japan is preparing to field a 3,000-strong amphibious force as rapidly as possible to defend offshore islands.

The Japanese military is trying to establish full-scale amphibious operational capability as soon as possible because of an increasingly severe security environment surrounding Japan, a Japanese Defense Ministry spokesman said in an email this month.

The Japan Ground Self Defense Force includes high-mobility units but lacks a dedicated amphibious force, the spokesman said.

“It is necessary to newly develop sufficient amphibious operational capability in order to land, recapture and secure without delay in the case of an invasion of any remote islands,” he said.

Japan conducted extensive amphibious operations during World War II, but its current forces lack any real-world experience.

The country’s pacifist constitution has held back its military for more than six decades, but that could soon change; Japanese Prime Minister Shinzo Abe hopes to reinterpret Japan’s pacifist constitution, a move that could allow Japanese forces to act in defense of an ally.

Ralph Cossa, of the Center for Strategic and International Studies in Hawaii, said Tokyo’s efforts to build amphibious forces are particularly significant, especially as China renews territorial claims to islands long held by Japan, such as the Senkakus.

“Clearly the Japanese see the need (to have the ability) to retake islands,” Cossa said. “A certain party (China) seems to be the threatening their islands.”

Japan’s government wants to build several, regiment-sized amphibious units — comprising 3,000 personnel — and, to that end, it’s accelerating training and acquiring equipment such as tilt-rotor aircraft and amphibious vehicles, the ministry spokesman said.

“The ministry believes that it (the new amphibious force) will extend the range of interoperability with the U.S. Forces and possibly extend the range of joint training simulating disaster relief and humanitarian assistance with other forces, such as Australia,” the spokesman said.

The nucleus of the new force will be the Western Army Infantry Regiment, a highly mobile unit that has trained alongside U.S. forces in recent years. Last month, more than 200 Japanese soldiers practiced amphibious landings at Camp Pendleton, Calif., with U.S. Marines in Iron First, an annual exercise that has grown exponentially in recent years.

In June, a company of Japanese soldiers will train with U.S. and Australian troops during Exercise Southern Jackeroo at Puckapunyal, a military training area in the Australian state of Victoria.

Japan and Australia have become much closer to each other through tri-lateral co-operation with the U.S. in recent years, Cossa said.

“It’s unusual to see Japan exercising with others,” he said. But it’s “a step in collective self-defense that (Japanese Prime Minister) Abe wants to move to.”

For its part, Australia has been training 500 soldiers from the 2nd Battalion, Royal Australian Regiment on amphibious operations for the past 18 months, according to Brigadier Mick Ryan, director general of strategic plans for the Royal Australian Army.

So far the Australian force has focused on land-based training and familiarizing itself with its equipment, Ryan said.

But the addition of two new amphibious ships in the next 18 months means the regiment will soon be using landing craft and helicopters to go ashore. Training with the Australian Navy will be begin this summer, he said.

The Australian amphibious troops will hone their skills on various aspects of amphibious operations, such as planning, embarking, living at sea and moving from ship to shore, Ryan said.

The new force is expected to work closely with U.S. Marines, but it’s not modeled after them, he said.

Australia has a long history of amphibious operations, beginning with the failed 1915 Gallipoli landing by ANZAC (Australia and New Zealand Army Corps) troops in Turkey during World War I. The Australians also participated in numerous landings alongside U.S. forces in Southeast Asia during World War II and conducted amphibious operations in East Timor in 1999 and during the Indonesian tsunami response in 2004.

“It is a capability that, for an island continent, is a pretty important one to maintain,” Ryan said.

The Australians already have a strong relationship with the U.S. Marines, who share Robertson Barracks in Darwin with Australia’s 1st Brigade for six months of the year. This year, about 1,200 U.S. Marines will be based in Darwin, and that’s set to rise to a 2,500-strong Air Ground Task Force by 2015.

The Australians are focused on making sure their communications systems are integrated with the Marines and that there are common procedures for landing helicopters on ships and conducting resupply at sea, Ryan said.

Missions that the new force might be assigned to range from humanitarian assistance and disaster relief to noncombatant evacuation, he said.

robson.seth@stripes.com Twitter: @SethRobson1

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