The Department of Defence said Monday that it is closely watching the ongoing drills - the largest Russian war games in decades.
The online edition of the PLA Daily, the Chinese military's newspaper, says about 3,200 army and air force personnel and more than 1,000 armed vehicles are taking part in the exercise.
Dmitri Trenin, former Russian army colonel and director of the Carnegie Moscow Center think tank, opined that Russia is sending a strong message through Vostok 2018: "With its Vostok 2018 exercise Russia sends a message that it regards the U.S. as a potential enemy and China as a potential ally".
In this photo provided by Russian Defense Ministry Press Service on Wednesday, Sept. 12, 2018, Russian Defense Minister Sergei Shoigu, right, his Chinese counterpart, Gen. Wei Fenghe, left, and Russian Armed Forces Valery Gerasimov, center, visit the Tsugol firing range in eastern Siberia where almost 300,000 Russian troops and about 3,200 Chinese troops are participating in joint exercises.
Apart from China, a contingent of Mongolian troops will also be part of the games.
But Defense Minister Sergei Shoigu said the latest exercises are even larger.
- Vostok-2018 it includes 297,000 servicemen.
Florence Cahill, a senior analyst at a political risk consultancy firm, said Beijing and Moscow's closer ties demonstrate that trade wars and sanctions imposed upon them are only pushing them to strengthen their alliances.
Russian Federation said only 12,700 troops took part, but the Baltic States said the true number was far bigger.More news: New Hanover County declares state of emergency, considers mandatory evacuation
The previous Russian exercise involving a similar scale was in 1981 during the Cold War, but there are more troops in Vostok 2018.
"This is a milestone for Sino-Russian military ties", Alexander Gabuev, a senior fellow at the Carnegie Moscow Center, wrote on Twitter.
Russia's General of the Army Valery Gerasimov said Vostok runs from September 11 to 17 and has two stages.
The military exercises come amid escalating tensions between Moscow and the west over accusations of Russian interference in western affairs and conflicts in Ukraine and Syria.
The scale of Vostok-2018 is equivalent to the forces deployed in one of the big World War II battles, the BBC said.
North Atlantic Treaty Organisation spokesman Dylan White previously warned Russian Federation was building up its military strength.
China, for its part, may want to see the latest in military technology and advanced jet engines which Russian Federation possessed, Watling said.
Maintaining Russia's defence capabilities is "justified, needed and has no alternative" as rival powers are "frequently quite aggressive and unfriendly", Kremlin spokesman Dmitry Peskov said last month in comments carried by state news agency TASS.