MOSCOW, August 14 (RIA Novosti) – Some 20 units from a joint air defense system of the Commonwealth of Independent States (CIS), a bloc of former Soviet republics in Eurasia, have begun a large-scale exercise in Russia’s Volga region, a Russian Defense Ministry’s spokesman said Wednesday.

During the first stage of the Combat Commonwealth 2013 air defense exercise, the units from Russia, Belarus, Kazakhstan, Tajikistan and Kyrgyzstan will be redeployed to the Ashuluk firing range near the Caspian Sea where the active phase of the drills will take place, according to Col. Alexey Zolotukhin.

The three-stage exercise, which involves over 500 personnel and some 100 combat vehicles, will continue until September 12, Zolotukhin said.

Conducted annually, Combat Commonwealth exercises are part of efforts to build a joint air defense shield for the CIS. An integrated air defense network was set up by 10 CIS member countries on February 10, 1995.

The main purpose of the network is to ensure the protection of the member countries’ airspace, as well as early warning of missile attacks and coordination of joint efforts to neutralize potential air threats.