About 300,000 Russian troops, 1,000 aircraft and 36,000 military vehicles are taking part in the exercise, which is the biggest in the country since Zapad-81 at the height of the cold war.
China's presence is being seen as a signal from both countries emphasizing their cooperation at a moment when Moscow and Beijing find themselves in a confrontation with the United States. According to reports, Chinese soldiers are also taking part in the war exercise for the first time.
North Atlantic Treaty Organisation spokesman Dylan White said the war games revealed "a more assertive Russia" which is "significantly increasing its defence budget and military presence".
President Vladimir Putin is expected to attend Vostok-2018 after hosting an economic forum in Russia´s far eastern city Vladivostok where his Chinese counterpart Xi Jinping is one of the star guests.
Xi, whose country is locked in a tense confrontation with the United States over trade and tariffs, said that Russian Federation and China should work together to oppose protectionism and what he called unilateral approaches to global problems.
Now, though, experts say the target audience of the drills is unambiguously not China, but the US and Europe instead.
The Russian army has compared the show of force to the USSR´s 1981 war games that saw between 100,000 and 150,000 Warsaw Pact soldiers take part in "Zapad-81" (West-81) - the largest military exercises of the Soviet era.
In the strategic drills, the PLA and Russian armed forces have formed a joint operational commanding system, under which military forces from the two countries will hold joint exercises including mechanized defense，fire strike and counter-attack training.More news: Storm Moving Closer to US
"China, by sending a PLA element to train with the Russians, is signalling that USA pressure is pushing it towards much closer military cooperation with Moscow".
Hong Kong-based commentator Song Zhongping said China was anxious to acquire more experience in large-scale operations that might become a factor in a conflict with the U.S. and others over territorial claims in Asia.
Russia´s previous military exercise in the region, Vostok-2014, was nearly half the size, with 155,000 soldiers participating.
In this photo provided by the Russian Defence Ministry Press Service on Tuesday, Sept. 11, 2018, a Russian soldier guards an area during the military exercises in the Chita region, Eastern Siberia, during the Vostok 2018 exercises.
Putin's spokesman Dmitry Peskov dismissed such concerns on Tuesday.
Whereas during the drills on its western borders last year, known as Zapad 2017, Russian Federation was accused of downplaying the number of troops involved, this year's war games are the opposite, with Moscow apparently eager to flaunt their scale.
"[It also] signifies that the political strategic trust and military cooperation between China and Russian Federation has reached a historic high".
"Imagine 36,000 military vehicles moving at the same time: tanks, armoured personnel carriers, infantry fighting vehicles - and all of this, of course, in conditions as close to a combat situation as possible", Shoigu said.
It involved deploying additional forces to Russia's far east and a naval build-up involving its Northern and Pacific fleets.