Helicopters buzzed in the shadow of a smoldering volcano and boats rescued dummies from the sea last week in a show of maritime unity by Japan, the United States and the Philippines.

Japan, the United States, and the Philippines carried out a major coast guard drills together on Friday. The drill took place in the waters off Kagoshima, a southern part of Japan. This event comes at a time when worries are growing about China’s increasing actions in the Pacific Ocean.

Japan’s coast guard has held a joint exercise with counterparts from the United States and the Philippines, as the three Pacific nations beef up defense cooperation in the face of China’s expanding maritime activities.