South Korea is worried about China's continued support for North Korea, and that growing Chinese military power will limit U.S. capacity to intervene if war breaks out on the Korean peninsula.

WSJ: Asia's New Arms Race

"The Chinese military is beefing up its power, " Mr. Abe said.

WSJ: Japan: Russian Fighter Jets Enter Its Airspace

One U.S. military adviser said Chinese military strategists see China becoming the dominant power in Asia by midcentury, by which time they believe the world will be divided into spheres of influence dominated by at least four great powers: China, the U.S., the European Union and Russia.

WSJ: New Beijing Leader's 'China Dream'

Too aggressive a Chinese military posture could produce a countervailing coalition among its neighbors that would weaken both its hard and soft power.

CNN: Don't fear the rise of China

Ni Lexiong, director of the Sea Power and Defence Policy Research Institute at the Shanghai University of Political Science and Law, says the Chinese military may have been reacting to provocation by Japanese naval vessels, Hong Kong's South China Morning Post reports.

BBC: Japan Maritime Self-Defense Force destroyer Yuudachi