The show of solidarity between the militaries comes at a time when the United States is beefing up ties with Japan and South Korea and NATO is looking to deepen its presence in the region, to the anger of China and Russia.

More than 10 warships and over 30 warplanes from both sides took part in the four-day "Northern/Interaction-2023" exercise as Chinese and Russian navies and air forces jointly planned and commanded naval and aerial escorts, deterrence and repelling exercises.

Chinese director of the drills Qiu Wensheng described the exercise as "a major move" in safeguarding the security of strategic waterways, while Rear Adm. Calery Kazkov of Russia, deputy director of the drill, said it had strengthened the ability of both sides to handle military threats, according to the Chinese statement.

The exercise is the latest gesture of enhanced military cooperation between China and Russia that has seen more frequent top military official interactions, as well as more military drills between the two.

It comes at a time of heightened military and security activity between the US and its major Asian allies.

Last month, the White House said national security advisers for the US, Japan and South Korea discussed maintaining stability in the Taiwan Strait and coordination over the East China and South China Seas.

Earlier this month, Japan and NATO agreed on a new partnership program, NATO chief Jens Stoltenberg expressing concern about China's military buildup. China on Monday warned Japan of NATO's expansion into the Asia-Pacific.

Against that backdrop are escalating tensions with North Korea, a longtime ally of China.

On Thursday, Pyongyang said deployment of US aircraft carriers, bombers or missile submarines in South Korea could meet criteria for its use of nuclear weapons.

For the first time since the 1980s, a US nuclear-armed ballistic missile submarine (SSBN) visited South Korea last week.

Evacuation drill

Meanwhile, cities across northern Taiwan ordered cars off roads and people to stay indoors on Monday for an annual air-raid exercise as the island steps up preparations in the event of a Chinese attack amid rising military threats from Beijing.

Sirens sounded at 1:30 p.m. for the mandatory street evacuation drills, which effectively shut towns and cities including its capital Taipei for 30 minutes.

An "air raid alert", asking people to evacuate to safety immediately, was sent via text message.

"When you receive the text message, please be aware of the wordings such as 'test' and 'drill' and stay calm," Taiwan President Tsai Ing-wen said in a reminder to the public on Facebook about an hour before the exercise named Wan An, which means everlasting peace.

China, which views democratically governed Taiwan as its territory, has been staging regular exercises around the island for the past three years, to pressure Taipei to accept Beijing's claim of sovereignty despite the island's strong rejections.

In the bustling shopping district of Ximending in Taipei, some shops pulled down their shutters and police directed passersby and vehicles including food delivery drivers on motorcycles to move to the side of the road and seek shelter.

Tourists with luggage were seen taking shelter in a subway station, some shocked and not sure what had happened.

"I heard the siren and I was worried, not knowing what happened especially we are foreigners in a foreign country," said Lee Jang Ho, a tourist from South Korea.

Among the various drills carried out by authorities in Taipei, some citizens were instructed to seek shelter in basement parking lots with their hands covering their eyes and ears while keeping their mouths open, to minimize the impact of blast waves from missiles.

Sirens sounded 30 minutes later to give the all-clear.