A leading think tank has responded to growing US and Japan military ties and what it described as their strategy of trying to contain China.

The report, jointly written by departments of the Chinese Academy of Social Sciences, is the fifth by the nongovernment think tank the China Strategic Culture Promotion Association since 2012.

Tokyo and Washington revised their military ties in 2015 under the Guidelines for Japan-US Defense Cooperation, which revealed "the intention of a closer Japan-US alliance to contain the rise of China", the think tank said.

Japan's defense budget for 2015 hit a record high of 5.19 trillion yen ($51 billion), which included a supplementary budget of 211 billion yen for the 2014 fiscal year.

The think tank also concluded that "by taking advantage of the US open engagement in disputes in the South China Sea", Japan is trying to "muddy the waters" in the region and is making a "military return" in Southeast Asia.

Luo Yuan, vice-president of the association, said part of the reason Japan is increasingly interfering in the South China Sea is that it wants to strengthen its alliance with the US.

The think tank cited the 2016 Defense Budget Proposal submitted by the administration of US President Barack Obama, saying that more than 30 percent of it was allocated to the US Navy.

By June 30 last year, the think tank said, the US military had more than 1.3 million personnel on active duty and had deployed more than 154,000 troops in the Asia-Pacific region.

Besides continuing to strengthen ties with traditional allies such as Japan and the Philippines, the US was expanding and deepening relations with India and Vietnam in 2015, the think tank said.