MOSCOW, January 17 (RIA Novosti) - An air defense regiment equipped with S-400 missile systems will go on combat duty in 2006, the commander of the Russian Air Force said Tuesday.

"Last year we completed the tests of the S-400 air defense system, and this year a regiment in the Moscow Region will be equipped with these systems and will go on combat duty," Vladimir Mikhailov said.

"All 35 air defense regiments will be re-equipped with the S-400 Triumf systems in the future," he said, adding that the Air Force would also receive several air defense systems from the Land Forces.

The S-400 (NATO designation SA-20 Triumf) is an advanced surface-to-air missile system designed to destroy aircraft, cruise missiles, and short- and medium-range ballistic missiles at ranges of up to 400 kilometers (250 miles).