Russia will next month hold its biggest war games of the post-Cold War era when it joins Chinese and Mongolian armies in a massive show of military strength.

Russian Defence Minister Sergei Shoigu said the exercise, called Vostok-2018 (East-2018), will take place in central and eastern Russian military districts and involve almost 300,000 troops, over 1000 military aircraft, two of Russia’s naval fleets, and all its airborne units.

The manoeuvres will take place at a time of heightened tension between the West and Russia, which is concerned about what it calls an unjustified build-up of the NATO military 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, which will take place from September 11-15, are likely to displease Japan, which has already complained about what it says is a Russian military build-up in the Far East.

Japanese Prime Minister Shinzo Abe is due to attend an economic forum in Vladivostok during the same period.

Mr Shoigu told Russian news agencies the war games would be the biggest since the Soviet-era Zapad-81 (West-81) exercises in 1981.

“In some ways they will repeat aspects of Zapad-81, but in other ways the scale will be bigger,” he told reporters while visiting the Russian region of Khakassia.

The Russian Ministry of Defence has confirmed that Chinese and Mongolian military units would take part in the exercise.

Kremlin spokesman Dmitry Peskov said the involvement of Chinese units showed Russia and Beijing were co-operating in all areas.

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, Mr 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 (the exercise) is justified and essential,” Mr Peskov told reporters on a conference call.

NATO spokesman Dylan White said that Russia had briefed the alliance on the planned exercise in May and that NATO planned to monitor it.

Russia had 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,” Mr White said in a statement.

“Vostok demonstrates Russia’s focus on exercising large-scale conflict,” he said.

“It fits into a pattern we have seen over some time: a more assertive Russia, significantly increasing its defence budget and its military presence.”

Mr Shoigu this month announced the start of snap combat readiness checks in central and eastern military districts ahead of the planned exercise.

“Imagine 36,000 armoured vehicles – tanks, armoured personnel carriers and armoured infantry vehicles – moving and working simultaneously, and that all this, naturally, is being tested in conditions as close as possible to military ones,” Russian agencies quoted Mr Shoigu as saying this week.

-with AAP