I wonder what the real reason for this announcement from Moscow is?

Russia has put defences on alert along its border with North Korea amid tensions over possible new missile tests by the secretive Communist regime.

The Kremlin ordered troops to deploy Russia’s most advanced missile defence system, the S-400, to intercept any threats from North Korea’s nuclear programme. General Nikolai Makarov, the head of the Russian army, said that a mobile battery of 32 surface-to-air missiles had been put into operation in anticipation of any Korean tests.

“We are taking these preventative measures as a security guarantee against faulty launches of the missiles and to guarantee that fragments of these missiles never fall on Russian territory,” he said. “We are concerned by the fact that the site in North Korea where it carries out its nuclear tests is located quite close to the Russian border.”  [Times Online]

If I had to guess I would think the Russians are just deploying the system to its Far East in order to track North Korean missiles to test its new radar against a real threat target.  Additionally as NK Econ Watch points out, the Russians are using the North Korean threat as an excuse for a military build up in the region as well.

Anyway here are some details about the S-400 missile defense system:

The new Russian air defence S-400 Triumf system is capable of hitting radar reconnaissance and AWACS planes, which raises considerably its competitiveness on the world arms market, says the article “Triumf is put on alert”, published in the May issue of the Voenny Parad journal which is now being put on sale and is distributed among subscribers. The S-400 is designed to hit modern and future attack aircraft at a distance of 400 km: tactical and strategic aviation jets, cruises of the Tomahawk type and other missiles”, the article notes. Triumf successfully fights air targets, manufactured with the use of “stealth” technology at all altitudes of their combat operation and at maximum distances. When creating this system, Russian specialists used latest technologies in the radar industry, microelement base and computer engineering. In the opinion of general designer Vladimir Svetlov, Triumf is the world’s first system which can selectively work with the use of several types of missiles. “The long-range missile has no analogues. It eclipses the American Patriot-3 system by around 100 percent, as does the French Aster, he claimed.  [FAS]

According to this Pravda article, this system’s radar has some significant issues, which only adds further reason why they would want to have this system deployed and tracking real life targets.