Russia's Pacific Fleet divisions take position in Kamchatka.
Strategic bombers redeployed Eastern Military District in snap exercises called by Vladimir Putin.
Moscow has confirmed moves to modernise its military presence on islands over which Japan claims sovereignty.
Troops and government ministries checked 'for fulfilling tasks under wartime conditions'.
100,000 troops and 5,000 weapons involved in the exercises in the Eastern Military District.
Based near Anadyr, its role is to 'monitor combat readiness' of military units, survey terrain, and air patrols.
Defence Ministry move seen as bolstering Russia's eastward tilt.
'Spy plane' was monitoring Siberia under Open Skies treaty aimed at reducing tension after Cold War.
The mayor of Vladivostok is fed up with Moscow being asleep when he needs key decisions to be made.
Flights late on Thursday and on Friday suffered disruption due to smog caused by blazes in dry woodland made vulnerable by the current heat wave.