China's military build-up, and growing defence ties among Washington and its allies have raised fears of a conflict over self-ruled Taiwan -- which Beijing claims as its own -- or over other territorial disputes in the region.

"Keen Sword" will involve 45,000 Japanese and US troops, 40 vessels and 370 aircraft, as well as some forces from Australia and Canada, the Japanese Joint Staff said.

The exercises, which take place every two years, will be held across Japan, including at the two countries' military bases through November 1.

"We have a strong sense of urgency that we can't rule out the possibility of a serious situation resembling Ukraine happening in regions near our country," General Yoshihide Yoshida, the top uniformed officer in Japan's Self-Defense Forces (SDF), said on Tuesday.

"We are determined to prevent and deter such a situation," he told a news conference, adding the US-Japan alliance was integral to regional stability.

"Keen Sword will ensure we maintain our advantage over those who seek to undermine the rule-based international order", Admiral Steve Koehler, commander of the US Pacific Fleet, told reporters Tuesday.

The exercises will see tilt-rotor aircraft Ospreys fly to Yonaguni, the Japanese island closest to Taiwan, for the first time, as part of an "evacuation" drill, an SDF spokesman told AFP.

The drill was to practise bringing out residents and tourists "in the event of a natural disaster", he said.

Japan's new Prime Minister Shigeru Ishiba has also evoked Russia's invasion of Ukraine in warning about security dangers in Asia.

"Many fear that today's Ukraine could be tomorrow's East Asia. Why did deterrence not work in Ukraine?" Ishiba told parliament this month soon after being elected.

Ishiba, facing a difficult snap election on Sunday, backs the creation of a regional military alliance along the lines of the Western bloc NATO, although he has cautioned this would "not happen overnight".

In August, a Chinese military aircraft staged the first confirmed incursion by China into Japanese airspace, followed weeks later by a Japanese warship sailing through the Taiwan Strait for the first time.

Earlier Wednesday, Taiwan's defence minister said a Chinese aircraft carrier group sailed through the sensitive Taiwan Strait, a day after Beijing held a live-fire exercise near the island.

It followed China's large-scale military drills around Taiwan last week that were condemned by Taipei and its key backer Washington.

A blockade of the island was among the exercises carried out by Beijing, which has refused to rule out the use of force to bring Taiwan under its control.

tmo/stu/sco

ADMIRAL GROUP