Tokyo is planning to boost surveillance in waters around the Diaoyu Islands and acquire the ability to launch pre-emptive military strikes in a defense policy update that may set off alarm bells in China.

According to a preliminary report by Japan's Defense Ministry, acquired by Japanese media on Thursday, the ministry is also considering deploying unmanned surveillance drones and creating an amphibious force modeled after the United States Marine Corps to protect remote islands, according to Japan's Kyodo News Agency.

The full report is expected on Friday and will reveal that the ministry wants to have the ability to launch pre-emptive ballistic missile strikes.

Since taking office in December for his second term, Prime Minister Shinzo Abe has vowed to bolster the country's military. Chinese observers said Japan has been expanding its military forces rapidly over the years to counter what it claims is an increasing threat from China.

Sino-Japanese ties have been strained in recent years after Japan claimed sovereignty over China's Diaoyu Islands in the East China Sea and illegally nationalized the islands last September.

"Japan has fostered strong maritime forces in Asia and it is now upgrading its air force," said Su Hao, a professor of Asia-Pacific studies at China Foreign Affairs University.

On Thursday, Chinese Defense Ministry spokesman Geng Yansheng said Beijing is aware of Japan's military buildup and will monitor further developments.

The report is part of a review of Japan's National Defense Program Guidelines undertaken by Abe's administration. Final reports from the review are due by the end of the year.

The updated defense policy may indicate that Abe is moving toward exercising the right of collective self-defense.

Tokyo plans to buy 42 Lockheed Martin F-35 stealth fighters, with the first four due for delivery by March 2017.

"Military nationalization, along with his other right-wing political claims, are on Abe's agenda," Su said. "Huge investments in defense buildup will also feed domestic military industries and therefore contribute to the stagnant economy."

Japan last updated its National Defense Program Guidelines in 2010, shifting its defense focus from the north to the south, where it claims sovereignty over China's Diaoyu Islands.

Su said Japan is cooperating with the US military in the Asia-Pacific as the latter shifts its strategic focus to the region.

The Japanese Defense Ministry plans to send its Senior Vice-Minister Akinori Eto to the US at the end of this month to consult with US Deputy Secretary of Defense Ashton Carter on the progress Japan has made in reviewing its long-term defense policy, the Kyodo News reported.

At present, a regiment of Japan's ground forces has been shifted to a more amphibious role. A new unit will then be created by combining ground, marine and air forces.

Japan is hoping its joint military exercises with the US will strengthen its amphibious ability to retake remote islands from an enemy force. In June, joint forces from the US and Japan conducted amphibious training in California.

The Japanese Defense Ministry is also looking into acquiring amphibious vehicles and aircraft to transport troops without the need for airstrips, such as the MV-22 Osprey used by the US Marines, the Sankei Shimbun said. The tilt-rotor Osprey takes off and lands like a helicopter but can cruise like a fixed-wing airplane.