NATO to monitor Russia's September drill of 300,000 troops, 1,000 aircraft, two naval fleets and all its airborne units.
Russia will hold its biggest war games in nearly four decades next month, a massive military exercise that will also involve the Chinese and Mongolian armies.
The September 11-15 manoeuvres will involve almost 300,000 troops, more than 1,000 military aircraft, two of Russia's naval fleets and all its airborne units, Russia's Defence Minister Sergei Shoigu said in a statement on Tuesday.
Shoigu said the drills "are on an unprecedented scale both in terms of the area covered and in terms of the numbers" of military forces.
"Imagine 36,000 pieces of military equipment moving together at the same time - tanks, armoured personnel carriers, infantry fighting vehicles. And all of this, of course, in conditions as close to combat as possible," he said.
The exercises in central and eastern Russia, dubbed Vostok-2018, will take place at a time of heightened tensions between the West and Russia, which is concerned about what it says is an unjustified build-up of forces by the NATO alliance on its western flank.
NATO says it has beefed up its forces in Eastern Europe to deter potential Russian military action after Moscow annexed Ukraine's Crimea in 2014 and backed a pro-Russian uprising in eastern Ukraine.
The war games are also likely to displease Japan, which has complained about what it says is a Russian military build-up in the Asia-Pacific.
China's state Xinhua news agency has reported Beijing plans to send 3,200 troops and about 900 weapons units for the exercises.
Japanese Prime Minister Shinzo Abe will attend a forum in Vladivostok over the same period. A foreign ministry official said on Tuesday that Tokyo always pays attention to shifts in Russian-Chinese military cooperation.
When asked if the cost of holding such a massive military exercise was justified at a time when Russia is faced with higher social spending demands, Kremlin spokesman Dmitry Peskov said such war games were essential.
"The country's ability to defend itself in the current international situation, which is often aggressive and unfriendly towards our country, means [it] is justified," Peskov told reporters on a conference call.
'More assertive Russia'
When asked if China's involvement meant Moscow and Beijing were moving towards an alliance, Peskov said it showed the two were cooperating in all areas. China and Russia have taken part in joint military drills before, but not on such a large scale.
NATO spokesman Dylan White said Russia had briefed the alliance on the planned exercise in May and NATO planned to monitor it.
Russia invited military attaches from NATO countries based in Moscow to observe the war games, an offer he said was under consideration.
"All nations have the right to exercise their armed forces, but it is essential that this is done in a transparent and predictable manner," White said.
"Vostok demonstrates Russia's focus on exercising large-scale conflict. It fits into a pattern we have seen over some time: a more assertive Russia, significantly increasing its defence budget and its military presence."