Moscow and Beijing have deepened military and economic cooperation in recent years, as both countries seek to counterbalance what they see as a United States-led global order.

Russia's Ocean-2024 exercise will take place in the Pacific and Arctic as well as the Mediterranean, Caspian and Baltic Seas and is the first of its type "in the last three decades", Putin said in a televised address.

"Under the pretext of countering the alleged Russian threat and containing the People's Republic of China, the US and its satellites are increasing their military presence near Russia's western borders, in the Arctic and in the Asia-Pacific region," Putin said.

"Russia must be prepared for any development of the situation," he added.

He said the drills were aimed at testing the "combat readiness" of Russia's military leadership, without elaborating.

The drills will involve more than 400 warships, submarines and support vessels and last until 16 September, according to the Russian defence ministry.

China sent four warships and a supply vessel to the exercise, joining Russia's naval fleet in the Sea of Japan, it said.

Also taking part are "more than 120 aircraft and helicopters ... about 7,000 units of weapons, military and special equipment, and more than 90,000 personnel," the ministry added.

The Japanese defence ministry said it had observed five Chinese naval ships entering the Sea of Japan heading in the direction of Russia over the weekend.

It "confirmed that these vessels sailed north-eastwards through the Tsushima Strait towards the Sea of Japan from Saturday to Sunday".

Japan's Self-Defence Forces "conducted vigilance monitoring and intelligence gathering" with a vessel and patrol plane, the ministry said, releasing photos of the ships.

The Tsushima Strait lies between South Korea and Japan and connects the South China Sea and the Sea of Japan -- known as the East Sea to Koreans -- and is not within Japanese territorial waters.

- Rising tensions -

In his address at the opening of the drills, Putin accused Washington of spurring a global arms race and said Moscow had the right to defend its interests.

"The United States is provoking an arms race without regard for the security of its European and Asian allies, and is creating the preconditions for a dangerous crisis situation in Europe and the Asia-Pacific region," Putin said.

"Our armed forces must provide reliable defence of Russia's sovereignty and national interests and repel possible military aggression in any direction, including in the ocean and maritime zone," he added.

Russia and China have ramped up military cooperation in recent years, with both railing against "Western hegemony", particularly what they see as US domination of global affairs.

China's growing economic and military clout and its assertiveness in territorial disputes, most recently with the Philippines, has also rattled the United States and its allies.

On August 26, Japan scrambled fighter jets after what it called the first confirmed incursion by a Chinese military aircraft into its airspace.

Last week, Japan protested after a Chinese naval ship entered its territorial waters.

Japan and Russia also have a territorial dispute over the Kuril Islands -- known in Japan as the Northern Territories -- and their relations have deteriorated sharply since the start of the Ukraine conflict.

Japanese and Chinese vessels have been involved in tense incidents in other areas, in particular, the remote Senkaku islands in the East China Sea claimed by Beijing, which calls them the Diaoyus.

Tokyo has reported the presence of Chinese coastguard vessels, a naval ship and even a nuclear-powered submarine in the area, and there have been a series of confrontations between Japanese coastguard vessels and Chinese fishing boats.