China is sending about 3,200 troops, 900 combat vehicles and 30 aircraft to join the drills at a Siberian firing range, a significant deployment that reflects its shift toward a full-fledged military alliance with Russian Federation.
He said China feels Washington's hostile attitude and actions, such as deploying the THAAD missile defence system in South Korea, relieve it of any need to take United States views into consideration when deepening strategic trust with Moscow.
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.
For his part, Xi said the two countries' "friendship is getting stronger all the time".
Russian military analyst Pavel Felgenhauer said the games were a "preparation for a future world war".
Hundreds of Chinese armoured combat vehicles, attack helicopters, fighter jets and thousands of soldiers take part in the biggest military exercise in Russian Federation since 1981, in a show of strength and friendship between Asia's two largest military powers.
North Atlantic Treaty Organisation has already condemned the war games as a rehearsal for "large-scale conflict" - and experts say they are without doubt the largest in modern Russian history.
Putin, who is armed forces commander-in-chief, is expected to observe the exercises this week alongside Defence Minister Sergei Shoigu, who is overseeing them.
The exercise will be carried out in five army training grounds across the Sea of Japan, Bering Straits and Sea of Okhotsk.
Russian Federation will showcase some of its latest military hardware at Vostok-2018, including nuclear-capable Iskander missiles T-90 tanks and Su-35 fighter jets.More news: Trump Team, Canada Officials Carry on Talks to Revamp NAFTA
At sea, the Russian fleet is deploying several frigates equipped with Kalibr missiles that have been used in Syria.
Some of the first exercises will revolve around anti-aircraft technology, according to Russia's defence ministry.
Putin's spokesman Dmitry Peskov argued the exercises were "justified" in "the current global situation" given "aggressive and unfriendly" attitudes towards Russian Federation.
Putin's 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", White said.
Russia´s previous military exercise in the region, Vostok-2014, was nearly half the size, with 155,000 soldiers participating.
Given the declining and increasingly acrimonious state of relations since Russia's annexation of Crimea in 2014, Putin "wishes to be as best prepared as possible to prevail in open warfare as well", Giles added.
Since then Moscow has increased the number of its large-scale military exercises in the Caucasus, the Baltic and the Arctic.
Russian Federation said only 12,700 troops took part, but the Baltic States said the true number was far bigger.