MOSCOW, February 10. /TASS/. Russia’s S-400 surface-to-air missile systems have been put on combat duty at a training range in Belarus’ Brest region as part of the Russian-Belarusian unified regional air defense system during an inspection of the Union State’s troops, the Russian Defense Ministry said in a statement on Thursday.

"The combat crews of the Russian Eastern Military District’s S-400 surface-to-air missile system went on combat duty to ensure air defense as part of the unified regional air defense system of Russia and Belarus during the inspection of the Union State’s troops," the statement reads.

According to the ministry, service members "have taken on the task to monitor airspace in the designated area of responsibility."

The Russian Defense Ministry announced earlier that the inspection of the response forces of the Union State of Russia and Belarus would take place in two stages. The first stage, which lasted until February 9, included the redeployment of troops and the creation of task forces in Belarus, as well as activities to ensure the security of crucial government and military facilities and protect the state border in the airspace. In addition, the preparedness and capabilities of air defense quick reaction alert forces in terms of shielding crucial facilities were also checked.

The Union Resolve drills are being held at the second stage of the inspection on February 10-20, with troops practicing ways to repel external aggression, combat terrorism and protect the interests of the Union State.