By Ruairidh Villar
ENIYABANAREJIMA, Japan (Reuters) - Japanese land, sea and air forces combined to simulate the recapture of a remote island on Thursday, a small drill that nonetheless underscores the country's concerns about far-flung territory claimed by China.
Bobbing silently into a cove on rubber boats and wielding plastic training rifles, about 50 troops training for a new marine force landed on the uninhabited outcropping, the size of 30 soccer fields, 600 km (370 miles) northeast of a string of islands held by Japan but claimed by China.
"Our amphibious warfare skills still have a way to go and our training is in its early days," said Gen. Shigeru Iwasaki, chief of the military's Joint Staff, Japan's top uniformed officer.
"But these capabilities are absolutely vital to protecting our land, sea and skies," he told reporters gathered on Eniyabanarejima, part of an island chain between the southern main island of Kyushu and Okinawa. "We intend to build on this drill today to boost our skills in the future."
The joint exercise of the Self-Defense Forces was not aimed at any specific country, said Chief Cabinet Secretary Yoshihide Suga. But Tokyo identifies its giant neighbor as a key source of concern and defending remote islands as a policy priority.
Chinese Foreign Ministry spokesman Hong Lei criticized the drill, saying that "moves taken by Japan in the military and security field have always been of high concern to its Asian neighbors".
"We require the Japanese side to make clear its true intention of the relevant deployment," Hong told a daily news briefing in Beijing. "We also call on the Japanese side to do more conducive things to safeguard regional peace and stability."
The dispute over the Japanese-held islets, which Tokyo calls the Senkaku and China claims as the Diaoyu, has raised fears of a clash between Asia's biggest powers that could even drag in the United States.
Prime Minister Shinzo Abe, chafing at the constraints of Japan's pacifist post-war constitution, has made a priority of a more robust military posture and a less-apologetic diplomacy. Abe has reversed a decade of defense-spending cuts with small increases and is calling for a review of legal limits on the ability of Japan's armed forces to fight overseas.
The military last month began its first expansion at the western end of its island chain in more than 40 years, breaking ground on a radar station on a tropical island near Taiwan.
In Thursday's exercise, troops scanned the beach for enemies, then marched single-file into the jungle. They later returned to the beach to collect huge backpacks from the boats and pushed once more into the interior of the 30 ha (75 acre) island.
The first combined-services drill in Japan on retaking an island was a modest undertaking involving 1,300 personnel, two destroyers, two F-2 fighter jets, a carrier for troops and amphibious vehicles, a minesweeper and a handful of helicopters.
AMPHIBIOUS ASSAULT FORCE
But in addition to signaling Tokyo's keenness to protect its thousands of small islands, it is the latest step in forging a unified amphibious assault force capable of fighting without support from its U.S. ally.
"Amphibious operations that combine naval, ground and air forces are one the most difficult military operations," said Grant Newsham, a former U.S. Marine liaison officer to Japan's Ground Self-Defense Force.
"Japan is showing that it will do what is necessary to defend itself, ideally alongside the Americans, but alone if necessary," said Newsham, a research fellow at Japan Forum for Strategic Studies.
Despite controlling vast ocean territories, Japan had no significant amphibious units until it began training the marine force in 2012.
A legacy of inter-service rivalry - stretching back to the Imperial Army and Navy before and during World War Two - has also made combined operations difficult to stage, analysts say.
Concern over China, and Abe's push for a more assertive military, are spurring the top brass to put their differences aside.
Japan "has gone from a standing start to having a serviceable amphibious capability in an astonishingly short time," said Newsham. U.S. military planners, he added, were impressed by the Japanese marine force during their participation alongside U.S. forces in landing drills in California last year during operation Dawn Blitz.
New equipment on Abe's military shopping list are set to add to that capability, including amphibious assault vehicles able to drive troops from the sea inland and tilt-rotor aircraft such as the U.S. Osprey.
(Additional reporting by Tim Kelly in Tokyo and Sui-Lee Wee in Beijing,; Editing by William Mallard and Ron Popeski)