Russia began a large-scale military exercise on Monday in its southern military district, near neighbouring Ukraine.
The Caucasus-2016 exercise, which will last until the end of Saturday, includes 12,500 servicemen, as well as warplanes, army vehicles and ships of Russia's Black Sea Fleet and Caspian flotilla, the Defence Ministry said in a post on its Facebook page.
Last month, Russia conducted a massive snap check of its military forces in areas near Ukraine and the NATO member Baltic states amid an escalation in tensions between Russia and Western-backed Ukraine.
Russian state news agency TASS reported last month that long-range S-400 missile systems, capable of hitting airborne targets up to 400 kilometres away, were being deployed to Crimea, a disputed peninsula that Russia annexed from Ukraine two years ago.
The report said Russia would showcase the missile systems during the Caucasus-2016 exercise.