Russia's defense chief arrived on Thursday in Crimea for a surprise combat readiness check.
Flying over troop deployments in the area, Defense Minister Sergey Shoygu checked the readiness of naval and land troops for military exercises, the ministry said in a statement.
Shoygu later launched the exercises of the Russian Black Sea and Caspian Sea fleets, as well as airborne forces, engaging over 10,000 military staff, 1,200 units of weapons and military equipment and 40 vessels, the statement added.
The exercises take place amid escalating tensions in southeastern Ukraine. Kyiv and separatists accuse each other of violating a truce between them.
Ukraine also accuses Russia of sending troops to the border, while Moscow says its moves are in response to "Kyiv's provocative actions," saying its western neighbor is preparing an offensive aiming to secure a military solution to the conflict with the possibility of hostilities on the border.