Moscow, Dec 20 

Russia has not deployed its Iskander tactical nuclear missiles in Kaliningrad, President Vladimir Putin said Thursday.

"Iskander is not our only means of defense and response to the threats that we see around us. Iskander is only one of the elements of a possible response, and it is far from being the most efficient one, although it is the most efficient weapon in the world in its segment," Xinhua reported citing Putin telling reporters during his annual major press conference.

NATO's missile shield threatened Russia's nuclear potential, so Russia must respond, and deploying Iskanders in Kaliningrad was just "one possible response," he said.

On Monday, the Russian defence ministry said in an ambiguously worded statement that Iskander missiles had been stationed in Russia's Western Military District, which includes Kaliningrad, as well as much of the European part of Russia.

Following the statement, representatives of a number of NATO nations expressed concern that, if true, the move would represent a deepening of tensions with Russia.

The US voiced its concerns over the missile deployment and urged Moscow not to undertake "destabilising steps".

Russian Defense Minister Sergei Shoigu said Moscow was not going to sit idly watching the US deploy the anti-missile defence shield in Europe.

"Our scientists, designers and plants work very efficiently. Russian weapons are powerful, mobile and efficient. We've got to respond," the minister said.