Russia's Defense Ministry says it has kicked off air-force exercises in the Ural Mountains and Western Siberia involving 12,000 soldiers and 250 aircraft.
The maneuvers, which began on May 25 and are to last until May 28, are meant to help the military prepare for a larger drill in September, called Tsentr-2015.
After Moscow's annexation of Ukraine's Crimea region in March 2014, Russia has held numerous large-scale military drills checking combat readiness.
In a statement on its website, the ministry described the drill as a "massive surprise inspection," to check combat readiness and develop a command system in field conditions.
The statement added that the drills in the Central Military District have been reinforced by units from the Western and Southern military districts as well as long-range aircraft.
A ministry spokesperson said that, during the exercise, "Long-range aviation aircraft will carry out cruise missile strikes against a mock enemy's ground targets at the Pemboi test and training area [in the Komi Republic]."
Asked about Russia's assertiveness in a television interview, Deputy Prime Minister Dmitry Rogozin joked that "tanks don't need visas."
Based on reporting by Reuters and AFP