MOSCOW, September 23. /TASS/. Deployment in South Korea of U.S.’ THAAD ant-missile system affects Russia’s interests and will be taken into consideration in defense planning, Mikhail Ulyanov, head of the Foreign Ministry Department for Non-Proliferation and Arms Control, said on Friday.

"We can see that in the Korean Peninsula South Korea’s authorities alongside the United States increase military activity that provokes Pyongyang into taking new thoughtless steps," Ulyanov said. "The deployment of US anti-missile defense units in South Korea is transforming into a practical sphere."

"We can see as a result the tensions are spiraling," he said. "One country’s actions cause a response from others and in this way they may proceed endlessly up to a really serious cataclysm. It’s very dangerous."

"Deployment of these anti-missile defense units affects the interests not only of Pyongyang but both of China and, to a certain degree, of Russia," said. "It will be taken into account in defense planning of China, Russia and North Korea."

The decision to deploy the THAAD in the south of the Korean Peninsula was made at the beginning of July. The ground-based missile defense system is designed to intercept the warheads of ballistic missiles at the end of the mid-course phase and during the approach to the target, and also to protect cities and key facilities from ballistic missiles - both short-range and strategic ones. A nuclear missile threat from North Korea was named as the reason for stationing a THAAD unit on the permanent basis. Russia and China are strongly against these plans.