In its annual white paper, the ministry outlined its stance on issues from tensions around Taiwan to the intensifying rivalry between China and the United States.

Repeated joint sorties by Chinese and Russian ships around Japan "are clearly intended as a demonstration of force against Japan and are a grave concern from the perspective of national security," it said.

North Korea, meanwhile, which often conducts missile tests in Japan's direction, poses a "more grave and imminent threat to Japan's national security than ever before".

In previous years, the defence paper has raised the need to counter regional threats including growing Chinese military clout and a nuclear-armed North Korea.

Japan plans to double its defence spending to the NATO standard of two percent of GDP by 2027, although the falling value of the yen may dent its purchasing power.

This year, the paper noted that Beijing regularly sends ships to areas close to disputed islands in the East China Sea -- reiterating that China's military ambitions are "the greatest strategic challenge" to Japan and the world.

It seems China intends to make increased military activities around Taiwan a new normal for the region, said the paper, which also listed heightened defence risks associated with AI, cybersecurity and disinformation.

"The international community is facing its greatest trial since World War II and competition among states, especially between the US and China, and it is set to intensify," the white paper said.

Japan is forging closer defence ties with like-minded countries in the region including Australia and South Korea, and on Monday signed a key defence pact with the Philippines to allow the deployment of troops on each other's territory.

The Philippines and Japan are both longtime allies of the United States, which has been strengthening defence ties in Asia to counter China's growing military might and influence.

Chinese officials have accused the United States of trying to create an Asia-Pacific version of NATO.

On Thursday, Japan's top government spokesman declined to comment on a report by Kyodo News that said a Japanese destroyer had made a rare entry into China's territorial waters this month, prompting a complaint from Beijing.