TOKUNOSHIMA, Japan- Japanese marines in amphibious assault vehicles stormed an island beach at the edge of the East China Sea on Sunday in a simulated attack to dislodge invaders from territory that Tokyo worries is vulnerable to attack from China.

As tensions run high with neighbours China, Russia and North Korea, the drill on the southwest island of Tokunoshima capped an 11-day series of exercises nationwide dubbed 05JX, meant to show the readiness of ground, sea and air forces to defend Japan's territory and infrastructure, including nuclear power plants.

"The goal of JX is to show that if there is an emergency situation resulting from an attack, that we are able respond in a joint way," General Yoshihide Yoshida, chief of staff of the Self-Defence Forces' Joint Staff, said after observing the drill on Tokunoshima.

Ground Self-Defence Force amphibious assault vehicles launched from two Maritime Self-Defense Force landing ships anchored offshore. Other troops arrived in semi-inflatable rubber boats, with heavy equipment carried to shore on military hovercraft.

Unlike many of the beaches along Japan's southwest island chain stretching toward Taiwan, the one on Tokunoshima does not have a coral reef that would make military operations more difficult.

The scope and pace of military exercises in Japan are likely to increase over the next few years, including with U.S. forces, after Prime Minister Fumio Kishida in December unveiled the country's biggest military buildup since World War Two, with a pledge to double defence spending over five years.

Kishida has warned that East Asia could be the next Ukraine, if China, emboldened by Russia's assault on its neighbour, attacks Taiwan.

The 43.5 trillion yen ($290 billion) in planned spending will go to new weapons such as longer-range missiles as well as to increase stocks of spare parts and munitions to fight a sustained conflict.

But the yen's sharp decline this year has forced Japan to cut back on some planned purchases, including new models of the U.S.-made Chinook helicopters that Japan's military used in the Tokunoshima drill.