Relations between Moscow and Beijing have always been marked by mutual wariness, with Russian nationalists warning of encroaching Chinese influence in the nation's mineral-rich far east, but Russia pivoted east toward China after the West sanctioned Moscow over its annexation of Ukraine's Crimean Peninsula in 2014 and trade links between the two, who share a land border more than 4,200km long, have blossomed since.
The show of military power includes Russia's Iskander missiles, which can carry nuclear warheads, as well as its Su-34 and Su-35 fighter planes.
Putin's spokesman Dmitry Peskov argued the exercises were "justified" in "the current worldwide situation" given "aggressive and unfriendly" attitudes towards Russian Federation.
Eighty warships are taking part and the Russian fleet is deploying several frigates equipped with Kalibr missiles - the same type that been used in Syria.
China has sent about 3,200 troops, 900 combat vehicles and 30 aircraft to join the drills at Tsugol.
The Russian military says the massive war games, known as Vostok-2018, are purely defensive in nature.
"It will be unprecedented in terms of geographic scope and the strength of command and control centers and forces due to participate", defence minister Shoigu said.
Wednesday will see games featuring anti-aircraft technology, while the main event will be on Thursday, the defence ministry told journalists covering the event in eastern Siberia and the Far East.
North Atlantic Treaty Organisation has denounced the exercises as a rehearsal for a "large-scale military conflict".
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 Kremlin spokesman, Dmitry Peskov, dismissed such concerns on Tuesday.
"It fits into a pattern we have seen over some time - a more assertive Russian Federation, significantly increasing its defense budget and its military presence", the alliance's spokesman Dylan White said last month.
They also serve as an exercise in "military muscle-flexing" to Russia's global rivals.
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 worldwide problems.
The war games are held a year after Russian Federation staged major drills in the country's west last September, unnerving neighbouring former Soviet republics.
Relations between Russian Federation and the West have been severely strained by Moscow's actions in Ukraine and Syria and its alleged interference in elections in the United States and European countries. Ukraine and the Baltic states said the true number was far bigger.