In its annual white paper -- a rundown of the most pressing military threats and plans to ensure stability -- Japan's defence ministry made a case for a significant hike in domestic defence spending as the world enters "a new era of crisis".

While China's growing military might and Russia's invasion of Ukraine were major focuses of the white paper, North Korea also ranked as a key concern for Japan.

"North Korea's military activities pose an even more grave and imminent threat to Japan's national security than ever before," the document said.

"It is believed that North Korea has the ability to attack Japan with nuclear weapons fitted to ballistic missiles."

The white paper, approved by the cabinet of Prime Minister Fumio Kishida on Friday morning, comes as North Korea ramps up the frequency of its missile tests.

North Korean state media on Thursday released photos of Kim Jong Un giving Russia's defence minister a tour of the country's newest and most advanced weaponry, including intercontinental ballistic missiles and previously unseen military drones.

Russia, another historic ally of North Korea, is one of a handful of nations with which Pyongyang maintains friendly relations.

Kim Jong Un has been steadfast in his support for Moscow's invasion of Ukraine, including, Washington says, supplying rockets and missiles -- a charge Pyongyang has denied.

Pyongyang's recent weapons tests -- the latest was on Monday -- come as Tokyo, Seoul and Washington increase military cooperation to counter the North's growing nuclear threats and China's influence in the region.

The white paper said China's military activities posed "an unprecedented and the greatest strategic challenge" to Japan while reiterating that joint military drills with Russia were also a concern.

China regularly sends government ships to islands in dispute with Tokyo while also conducting naval drills in waters including in the Pacific, raising alarm in Japan and area nations.

Beijing has not condemned Russia's invasion of Ukraine, with many leading democracies fearing China may also move to aggressively take over Taiwan.

"The international community is facing its greatest trial since World War II and we have entered a new era of crisis," Defense Minister Yasukazu Hamada said in the document.

The white paper reiterated Tokyo's commitment to boost its military spending and capacity.

For decades, Japan has capped military spending at around one percent of GDP.

But late last year, Kishida's government approved a plan to increase defence spending to two percent of GDP by fiscal year 2027, to around 11 trillion yen ($78.7 billion).