A US missile defence site in Romania aimed at protecting Europe from ballistic missile threats has been activated.
The move angered Russia, which opposes having the advanced military system in its former area of influence.
Nato secretary general Jens Stoltenberg tried to reassure Russia as he spoke at a ceremony attended by US, Nato and Romanian officials at the Soviet-built base, located 180km southwest of Bucharest.
The missile defence site “in no way undermines or weakens Russia’s strategic nuclear deterrent”, Mr Stoltenberg said at the opening ceremony.
"This site in Romania, as well as the one in Poland, are not directed against Russia.
“The interceptors are too few, and located too far south or too close to Russia, to be able to intercept Russian intercontinental ballistic missiles.”
He said the interceptors were designed “instead to tackle the potential threat posed by short and medium-range attacks from outside the Euro-Atlantic area”.
US officials said the Romanian missile shield, which cost $800 million (about €703 million), is intended to fend off missile threats from Iran and is not aimed at Russia.
Mr Stoltenberg noted that Moscow had unilaterally terminated co-operative dialogue about missile defence in 2013.
However, he said the alliance would continue to try and engage Russia in dialogue where possible.
“In times of tension, keeping channels of communication open is even more important,” he said.
Russian president Vladimir Putin's spokesman, Dmitry Peskov, said Moscow was already taking measures for "securing the necessary level of security in Russia".
‘Direct threat’
Admiral Vladimir Komoyedov, chairman of the state Duma’s defence committee, called the missile defence site a threat to Russia.
Mr Komoyedov, the former commander of the Russian Black Sea Fleet, told the Interfax news agency: “This is a direct threat to us.
“They are moving to the firing line. This is not just 100; it’s 200, 300, 1,000 per cent aimed against us.
“This is not about Iran, but about Russia with its nuclear capabilities.”
Romanian president Klaus Iohannis said his country wanted Nato to have a "permanent naval presence" in the Black Sea that respected international conventions, and called for increased security for Nato members in the south and east, which border Russia and the Middle East.
On Friday, Polish and US officials will take shovels in hand to break ground at a planned missile defence site in the Polish village of Redzikowo, near the Baltic Sea.
PA