MOSCOW, June 20 (RIA Novosti) - The first stage of the joint air defense exercise of the Commonwealth of Independent States has begun in East Siberia, a deputy commander of Russia's Air Force said Wednesday.

The Combat Commonwealth-2007 exercise involves Russia, Armenia, Belarus, Kazakhstan, Uzbekistan, and Kyrgyzstan, and will be held in four stages.

"Chief of combat training at the Air Force, Vladislav Stytsenkov, is overseeing the first tactical episodes: checking the permanent readiness of the Air Force and Air Defense high alert units and also simulated enemy attacks," Colonel Alexander Drobyshevsky said.

The first stage of the exercise is held at the Telemba training ground in East Siberia's Chita Region involving the Russian and Belarusian Air Force and Air Defense troops as well as Russia's Baltic Fleet.

The second stage will be held at the Ashuluk training ground in Russia's Astrakhan Region near the Caspian Sea in the second half of August. It will involve Russian, Armenian, Belarusian, and Kyrgyz forces.

The third and fourth stages will take place at Kazakh and Uzbek training grounds in August-September.

Conducted annually, such exercises are part of efforts to build an integrated security system for the Commonwealth of Independent States (CIS), a loose association of former Soviet republics. An integrated air defense network was set up by 10 CIS-member countries on February 10, 1995, but so far exists only on paper.