Japan is aggravating tensions with China over South China Sea issues to promote its own interests, according to experts who analyzed recent comments by Japan's new Defense Minister Tomomi Inada. On Thursday, Inada said that Tokyo is eying more patrols with the US and joint drills with regional navies.

Inada, speaking at the Center for Strategic and International Studies, a Washington, DC-based think tank, said Japan's increased engagement in the area would include capacity building for coastal nations, Reuters reported.

She also said she supports "the US Navy's freedom-of-navigation operations, which go a long way to upholding the rules-based international maritime order".

Su Xiaohui, a researcher on international strategies at the China Institute of International Studies, said Japan's interest in joint patrols mirrors its intention to promote its own interests in the South China Sea. Tokyo has a great deal of interest in conferring with nations in the area, including the Philippines and Vietnam.

"In light of the evolving US policy toward the South China Sea issue in recent years, Tokyo plans to offer more aid as a traditional US ally," Su said.

Su said it is expected that Japan will become more vociferous in the issue in the near future, but "it remains to be seen how much effect the US-Japan joint actions will take".

Foreign Minister Wang Yi told his Japanese counterpart Fumio Kishida in a Wednesday telephone conversation that the China-Japan relationship is "in a critical phase".

It is hoped Japan would do more "things that facilitate the improvement of the bilateral ties and things that facilitate ensuring maritime stability", Wang added.

Lyu Yaodong, an expert on Japanese diplomacy at Chinese Academy of Social Sciences, said Japan is seeking to whitewash its wartime role of invader in the region when it intervenes in the South China Sea issue.

"Japan will further expand its military presence in the region without offering tangible action to ease ties with China," Lyu said.