Chinese "coercive" naval actions in the China Sea region could trigger an incident, according to a new Japanese defense paper released on Tuesday.

The Japanese Prime Minister Shinzo Abe, along with his ministers at a cabinet meet, adopted the defense white paper. It is the first annual report on Japan's defense capabilities and regional security since the issue flared up afresh last year.

"China...has taken action described as coercive, which includes risky behavior," said the white paper.

"China's activities include its intrusion into Japan's territorial waters, its violation of Japan's territorial airspace and even dangerous actions that could cause a contingency," said the 450-page report.

Tensions between the two Asian countries have escalated since last September after Japan took three of the five islands, known as Senkaku in Japan and Diaoyus in China, out of private ownership.  For months, Tokyo and Beijing have  been exchanging severe warnings over intrusions into what both sides regard as their sovereign areas.

The islands lie in a very strategic area said to be rich in resources.

Referring to China's recent assertiveness over the Senkaku Islands, the U.S. Defense Secretary Chuck Hagel last month said ""The United States stands firmly against any coercive attempts to alter the status quo."

"In the South China Sea, the United States continues to call on all claimants to exercise restraint as they publicly pledged in 2002, and to seek peaceful means to resolve these incidents," said the U.S. defense secretary at an Asia Security Summit held in Singapore.