Russia has begun its biggest war games exercise since the fall of the Soviet Union close to its border with China, mobilising 300,000 troops in a show of force that will include joint exercises with the Chinese army.
China and Russia have staged joint drills before but not on such a large scale.
The drills, known as Vostok-2018 are taking place at a time of heightened tension between the West and Russia.
NATO has said it will monitor the exercise closely, as will the United States which has a strong military presence in the Asia-Pacific region.
Russia's Ministry of Defence broadcast images on Tuesday of columns of tanks, armoured vehicles and warships on the move, and combat helicopters and fighter aircraft taking off.
In one clip, marines from Russia's Northern Fleet and a motorised Arctic brigade were shown disembarking from a large landing ship on a barren shore opposite Alaska.
This activity was part of the first stage of the exercise, which runs until September 17, the ministry said.
The main aim is to check the military's readiness to move troops large distances, to test how closely infantry and naval forces cooperated, and to perfect command and control procedures.
Later stages will involve rehearsals of both defensive and offensive scenarios.
Russia also staged a major naval exercise in the eastern Mediterranean this month and its jets resumed bombing the Syrian region of Idlib, the last major enclave of rebels fighting its ally President Bashar al-Assad.
The location of the main training range for Vostok-2018 - 5,000 km east of Moscow - means it is likely to be watched closely by Japan, North and South Korea as well as by China and Mongolia, both of whose armies will take part in the manoeuvres later this week.
Russia also broadcast footage of some of 24 helicopters and six jets belonging to the Chinese air force landing at Russian air bases for the exercise.
Beijing has said 3,200 members of the People's Liberation Army (PLA) will join in.
When asked if he was concerned about a potential military alliance between Russia and China in the future, US Defence Secretary Jim Mattis said he did not see the two countries aligned in the long-term.
"I think that nations act out of their interest. I see little in the long-term that aligns Russia and China," Mattis told reporters in Washington.
Australian Associated Press