Vladimir Putin was spotted in military gear as he personally watched over military drills, including nuclear launch rehearsals, near Nato's border.
On Tuesday, the Russian President met with top military officials as the final day of drills took place in Russia's Nizhny Novogorod region.
According to Mr Putin, the drills were to ensure the "unconditional protection of the sovereignty and territorial integrity of the Union State", referring to the alliance between Russia and Belarus.
The two countries have just ended five days of war games which they called Zapad, meaning West.
The war games were undertaken in partnership with Belarus
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Belarusian leader Alexander Lukashenko said the exercises included a rehearsal of launching Russian tactical nuclear weapons.
Pavel Muraveiko, the Belarusian Chief of Staff, said the drills also included Russia's Oreshnik hypersonic missile - which was fired at Ukraine by Moscow for the first time on November 21 last year.
The war games involved an estimated 100,000 military personnel, and around 10,000 pieces of military equipment.
Mr Lukashenko added: "We are practising everything there. They [the West] know this took, we are not hiding it.
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Vladimir Putin was seen inspecting the war games in military fatigues
|REUTERS
"From firing conventional small arms to nuclear warheads.
"Again, we must be able to do all this. Otherwise, why would they be on Belarusian territory?"
He added: "But we are absolutely not planning to threaten anyone with this."
However, despite his assurances, many neighbouring countries have become wary of the alliance's military drills.
The military drills are thought to have included around 100,000 military personnel and around 10,000 pieces of military equipment
|REUTERS
Western military analysts have said the aim of the war games is to intimidate Europe
|REUTERS
Western military analysts have said the aim of the war games is to intimidate Europe and Nato, especially with the inclusion of Belarus.
The country not only borders both Ukraine and Russia, but also Nato members Poland, Lithuania and Latvia.
The former Soviet state hosts Russian nuclear weapons controlled by Moscow.
It allowed its territory to be used for Mr Putin's forces to enter Ukraine in February 2022, however, currently, no Belarusian troops have been committed to the fighting.
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