The amphibious troop unit of Japan's Self-Defense Forces conducted a joint exercise with the U.S. Marines on Sunday in southwestern Japan's Kagoshima, to prepare for operations to regain control of an enemy-held remote island.

The drill on Tanegashima Island is aimed at strengthening coordination between the allies on the back of China's maritime assertiveness around the Japanese-controlled Senkaku Islands in the East China Sea.

At around 6 a.m., five boats carrying members of the Amphibious Rapid Deployment Brigade of the Ground Self-Defense Force left the transport ship Osumi off Tanegashima and landed on the island. The drill was open to the press.

The Japanese and U.S. forces also conducted training to regain control of an enemy-held airport on the island with SDF and U.S. military personnel dropping off from an SDF CH-47 helicopter.

The members, carrying unloaded rifles, acted out an engagement with the assumed enemy.

Sunday's exercise, involving around 220 members from Japan's GSDF and 10 from the U.S. Marines, was the first amphibious drill conducted in Japan and follows one in Hawaii this summer. The joint exercise is scheduled to run through Friday.

"We improved our ability to conduct amphibious missions and the exercise was satisfying," Major Keisuke Komatsu, who commanded the Japanese amphibious unit that conducted the drill at the airport, said in a statement.

Speaking to reporters, Col. Mark Clingan, assistant division commander of the 3rd Marine Division, expressed hope of deepening coordination with the Japanese amphibious force unit.

The SDF's amphibious brigade started off with about 2,100 members and is stationed at the GSDF Camp Ainoura in Sasebo, Nagasaki Prefecture.

Despite a recent thaw in Sino-Japanese relations, the two countries remain at odds over the Senkaku Islands, a group of uninhabited islets that are called Diaoyu in China and claimed by Beijing.