Speaking in Bucharest, Assistant Secretary of State Frank Rose told a news conference before the system was made operationathat turning on the defense shield did not represent a security threat to Moscow, despite the Kremlin's concerns. The site is set to go live on Thursday.

"Both the US and NATO have made it clear the system is not designed for or capable of undermining Russia's strategic deterrence capability," Rose told reporters.

"Russia has repeatedly raised concerns that the US and NATO defense are directed against Russia and represents a threat to its strategic nuclear deterrent. Nothing could be further from the truth."

Work began on the facility in October 2013

Work on the Deveselu station, in the south of Romania, began in October 2013 and is estimated to have cost some $800 million (700 million euros).

The station will be equipped with a battery of SM-2 missile interceptors and will be officially inaugurated into the NATO missile defense shield at the organization's summit in Warsaw in July.

Kremlin concerns

Douglas Lute, the US ambassador to Romania, said the new station was an important part of Article Five of a NATO pact in which all 28 members are bound to come to each other's defense in the case of a military threat.

"Tomorrow is a demonstration that the US, Romania and the other allies contributing to the defense system mean what Article Five says," he said.

In spite of repeated assurances, the Kremlin maintains that the real purpose of the defense shield is to provide the US with enough military might to neutralize Russia's nuclear arsenal in order to make a first strike, in the event a war breaks out.

es/cmk (AFP, Reuters)