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 neighbors 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," Gen. Yoshihide Yoshida, chief of staff of the Self-Defense Forces' Joint Staff, said after observing the drill on Tokunoshima.