The Kremlin on Thursday insisted the deployment of a US missile defense system to Romania was a threat to Russia’s security.

The Kremlin on Thursday insisted the deployment of a US missile defense system to Romania was a threat to Russia's security.

"From the very beginning of this whole story, we have said that according to our experts' opinion, we are convinced that the deployment of the missile defense system is truly a threat to Russia's security," Kremlin spokesman Dmitry Peskov told reporters.   

A US missile defense interception station in Deveselu, southern Romania, became operational Thursday and will become part of a broader NATO missile shield to defend members against short and medium-range ballistic missiles.

Relations between NATO and Russia have severely deteriorated since Moscow annexed Crimea from Ukraine after a national referendum in March 2014.

Moscow has consistently accused NATO of trying to contain it since the collapse of the Soviet Union opened up the former Eastern Bloc.

US assistant secretary of state Frank Rose said Wednesday that the system was intended to counter threats from the Middle East above all and was not "designed for or capable of undermining Russia's strategic deterrence capability."

Vladimir Komoyedov, the head of Russia's parliamentary committee on defense, told Interfax news agency that the system's deployment was a "direct threat" to the country and that it would reinforce its military capacities.

Russia's defense minister Sergei Shoigu said earlier this month that Moscow was bolstering its forces to counter the "build-up of NATO forces in close proximity to Russia's borders."

"It is a step towards the military and political containment of Russia," senior foreign ministry official Andrei Kelin said of the deployment, Interfax reported. Kelin warned that it would "only worsen" the already tense relations between Russia and NATO.