Russian and Chinese commanders laid wreaths at a war memorial
Russian and Chinese armed forces have begun their first joint exercises, involving some 10,000 personnel.
Marines will storm beaches, to be joined by paratroopers in a mock invasion of an imaginary country.
The eight-day operation got under way in Vladivostok, in Russia's far east, with consultations between military delegations from the two countries.
Analysts say the two sides are signalling they are prepared to counter US dominance in international affairs.
The manoeuvres are being watched closely by Washington, but the US has not chosen to send official observers.
Known as Peace Mission 2005
Up to 10,000 personnel - as well as aircraft, warships and submarines
Russia and China clashed in the past over border issues, but relations have now improved
Russia is now one of China's top arms suppliers
"We are following the exercises," US State Department spokesman Sean McCormack said this week.
"We expect that they will be conducted in a manner that supports some mutual goal of regional stability shared by the United States, China and Russia."
They will be also be monitored in Taiwan, which China regards as a renegade province.
But China and Russia have stressed that the exercises, dubbed Peace Mission 2005, are not designed to intimidate.
"Our exercises don't threaten any country," General Yuri Baluyevsky, the head of the Russian armed forces general staff, told a news conference in Vladivostok.
General Liang Guanglie, chief of the general staff of the Chinese People's Liberation Army, said they were designed to "protect peace and stability in our region and the whole world".
He said they were part of the "fight against international terrorism, separatism and extremism".
China's military has been modernising rapidly
He denied the two countries were planning some kind of military union.
The exercises, involving air, sea, and ground units, involve mainly Chinese troops and will climax next week with an amphibious and paratroop landing on China's Shandong peninsula in the Yellow Sea.
Heralding the start of the drills, the Russian and Chinese commanders laid wreaths at a World War II memorial in Vladivostok before a Russian honour guard, and veterans from both countries also placed flowers there.