Japan may increase the size of its submarine fleet, officials said, as concerns rise that the expansion of the Chinese navy is tipping the regional balance of power.
The Defense Ministry said a bigger submarine fleet is under consideration, with a firm proposal likely to come as early as December. Officials who spoke to The Associated Press on Tuesday refused to give further details because the plan has not yet been formally tabled.
According to Japanese media reports, the number of submarines would be increased from 16 to 22 over the next four years, a substantial rise that could generate concern from neighboring China.
Though well outnumbered by the Chinese — who now have about 60 subs — the Japanese navy's submarine fleet is significantly augmented by U.S. subs deployed throughout the region. Japanese subs are generally believed to be better equipped than many of the Chinese vessels and are hard to detect.
Takehiko Yamamoto, a professor of international relations at Tokyo's Waseda University, said the move by Japan reflects a desire to counterbalance the Chinese navy's growth and to strengthen joint Japan-U.S. operations.
Yamamoto said Japanese military planners are particularly concerned that China is seeking to have a more credible "blue-water navy" that can operate farther away from its coastlines.
"That has created a sense of insecurity," he said.
He added that tensions or even clashes could erupt around the Okinawan islands in southern Japan — where Chinese subs have frequently been observed — or as far away as Guam, a U.S. territory where many of the American submarines in the Pacific are based.
Funded by annual double-digit increases in the defense budget over the past two decades, the Chinese navy has become Asia's largest and has expanded beyond its traditional mission of retaking Taiwan to push its sphere of influence deeper into the Pacific and protect vital maritime trade routes.
Beijing has also grown increasingly vocal in its demands for the U.S. to stay away from the wide swaths of ocean — covering much of the Yellow, East and South China seas — where it claims exclusivity.
China strongly opposed plans to hold U.S.-South Korean war games in the Yellow Sea off the northeastern Chinese coast, saying the participation of the USS George Washington supercarrier would be a provocation because it put Beijing within striking range of U.S. F-18 warplanes.
Concern over China's growing military capabilities and its claims to islands off its coasts has been heightened by recent maritime disputes, including a serious rift between Tokyo and Beijing over several remote islands in the East China Sea that both countries say is their sovereign terrritory. The area is believed to have reserves of natural gas which both Japan and China want to develop.
The dispute flared up recently when a Chinese fishing boat collided with Japanese patrol vessels in the area. Japan arrested and later released the captain of the boat, but the incident sparked diplomatic tensions and generated large anti-Japanese protests across China.
Japan and the United States have frequently criticized Beijing for increasing uncertainty in the region by refusing to be more transparent about the goals and capabilities of its military.
A recent Pentagon report said China was likely to sharply increase its own submarine fleet over the next several years.
It also said China is also developing a ballistic missile capable of attacking aircraft carriers more than 930 miles (1,500 kilometers) away — which could dramaticaly alter the ability of U.S. ships to operate in the region — and could start construction of an aircraft carrier of its own by the end of the year.
AP writer Christopher Bodeen in Beijing contributed to this report.