Russia launched month longed large-scale snap military drills, putting its troops on full combat readiness in districts bordering Ukraine and the Baltic States.
The drills is taking place in military districts that encompass the contested Crimea peninsula, the region that borders Ukraine and NATO members Estonia, Latvia and Lithuania, as well as territory spanning from the Ural mountains to central Siberia.
Relations between NATO and Russia have soured since Moscow annexed the Crimea peninsula of Ukraine in March 2014, and eastern European countries are worried that they too could be targets of Russian aggression.
Since Moscow annexed Crimea from Ukraine in March 2014, Russia has stepped up its military presence in the peninsula, which is home to its Black Sea fleet.
Russia’s most advanced air defence system, the S-400, was delivered to Crimea earlier this month.
NATO vowed at a summit in Warsaw in July to bolster its eastern flank to counter a resurgent Russia, agreeing to deploy four battalions in Poland and the Baltic states.