Japan has vowed to go ahead next week with a major military exercise testing US and Japanese troops' ability to recapture a hypothetical remote island, despite a complaint through diplomatic channels from Beijing.
Japan's participation for the first time in the US-led exercise was announced in Tokyo in April.
But it has taken on added significance given that President Xi Jinping will hold a two-day summit with President Barack Obama from today.
And while the US and Japanese Self-Defence Forces regularly conduct joint training exercises, the scenario for the two-week Dawn Blitz drills is likely to renew tensions over the sovereignty of the Japanese-controlled Senkaku Islands, which Beijing claims as its territory and knows as the Diaoyu Islands.
A spokesman for the Ministry of Defence in Tokyo declined to comment on the pressure that has been applied by Beijing, but confirmed: "We plan to start the exercises on June 10, and that has not changed." Some 250 troops from Japan's Western Army are taking part in the drill, on the Californian island of San Clemente, near the US Marine Corps' Camp Pendleton. Significantly, the Western Army is based in Kumamoto, in Kyushu prefecture, and its 15th Brigade is responsible for defending the Okinawa islands.
Japan's Ground Self-Defence units will also be supported by four GSDF helicopters and three other aircraft from the Maritime Self-Defence Force. The Japanese helicopter-destroyer Hyuga and guided missile destroyer Atago, as well as a transport ship, will also take part. About 1,000 Japanese personnel will be involved in the drills, which will also involve Canada and New Zealand.
"Originally, the exercise was to be conducted by US forces and this will be the first time our units take part," the ministry official said. "The exercise is aimed at enhancing joint operations with US forces and improving collaboration within the three arms of Japan's self-defence forces."
The operation is a step up from the joint exercise in Guam last September and based on a similar scenario. In that drill, just 40 Japanese ground troops practiced alongside the US marines.
In response to the request from Beijing for the exercises to be cancelled, Japanese officials have stated that the operation does not assume a specific third country as the adversary and the island being used in the scenario is only a hypothetical territory.
Defence officials added the practice landings are in line with an updated policy, under Japan's National Defence Programme, that requires the military to be able to defend the Nansei islands, at the extreme end of the Okinawan archipelago and close to Taiwan and mainland China.
Beijing expressed reservations when Japan launched the Hyuga, a new class of warship designed to make optimal use of helicopters, and its participation in the exercises in California could heighten concerns that Japan will further improve its amphibious landing capabilities.