Reuters JS Hyuga, rear, and JS Kurama sail in formation in Sagami Bay, Japan, last year. For the first time in the post-war era, Japanese ground troops will operate from Japanese warships far from home.

TOKYO – An unprecedented force of ships, troops and aircraft that Japan will send to southern California for amphibious warfare exercises next month represents only the first step in what leaders hope will be a transformation of its ground forces and national-defense strategy.

Instead of sticking to bases on their home islands, Japanese troops will be trained and equipped to seize islands and control territory across vast stretches of ocean.

And for this not entirely reassuring scenario, we can thank the growing military strength and assertiveness of China.

Japan announced plans this week to send three of its largest and most modern warships, along with 250 ground troops and combat helicopters, to take part in amphibious war games with U.S. Marines in and around Camp Pendleton, Calif.

Troops will spend several weeks learning to assault beaches, conduct helicopter and small-boat raids, work with pre-positioned supply ships and operate with U.S. and other multi-national forces. Troops and ships from Canada and New Zealand also will take part in the exercise, dubbed Dawn Blitz 2013.

Although Japanese ground troops have trained with Marines for a number of years, Dawn Blitz is by far the largest and most ambitious effort to date.

For the first time in the post-war era, Japanese ground troops will operate from Japanese warships far from home. Troops from the Western Army Infantry Regiment – which is being transformed into something resembling the U.S. Marine Corps – will board the JS Hyuga and JS Shimokita in Japan and sail across the Pacific to California. Others will join them during an expected stop at Pearl Harbor, Hawaii. A third ship, a guided-missile destroyer, will provide escort.

Japanese troops who have trained with Marines in California in the past have flown directly from Japan, operating for short periods from U.S. Navy ships just offshore. Learning how to live, train and fight from warships over extended periods of time and great stretches of ocean – and learning how to adapt those ships to accommodate hundreds of ground troops and their weapons and equipment — will be a key goal of the exercise. The Hyuga is the first of a new class of large, flat-deck helicopter carriers. It is designed primarily for anti-submarine warfare but can be adapted for other missions, like carrying troops or – potentially – short-takeoff and vertical–landing fighter planes like the new F-35. The Shimokita is a large transport with a submergible well deck that can accommodate air-cushioned landing craft. “The Japanese have about 80% of the hardware they need to put together an amphibious capability,” says Colonel Grant Newsham, U.S. Marine liaison officer with the Ground Self Defense Force (GSDF), in Tokyo. “Historically, the Japanese army and navy have not really cooperated well, and that continues up to this day. Developing their ability to do joint operations is something they need to work on.” Although no Japanese fighter planes will take part in Dawn Blitz, five officers from the Japan Air Self Defense Force will join the team. It’s one of the few occasions in which troops from all three of Japan’s armed services have taken part in a single exercise. The Japanese have debated whether to develop amphibious warfare capability for more than a decade. Thousands of small islands are scattered across Japan’s southwest island chain, with only a small garrison of ground troops on Okinawa (also home to about 18,000 U.S. Marines). The island chain stretches some 700 miles from the Japanese mainland. Chinese warships regularly transit the area on their way to the western Pacific.