President Vladimir Putin said on Thursday that Russia had not yet decided to place nuclear-capable Iskander missiles in the exclave region of Kaliningrad that borders the European Union.

"Firstly, we have not made such a decision yet. Let them calm down," Putin told reporters.

A Russian defence ministry spokesman had said earlier this week that Moscow had placed the Iskander missiles in the Western Military District, a region that includes Kaliningrad, in response to NATO's missile defence programme.

"Secondly, there is no need to defend anyone. There is no need to provoke anyone to take retaliatory steps," Putin said.

"American tactical weapons are located in Europe. No one in Europe controls them."

The Russian strongman indicated that Russia also had other weapons at its disposal to defend itself.

"The Iskander is just one of elements of a possible response -- by far not the most effective, although it's among the world's most powerful weapons in its segment."

The advanced version of the Russian missile has a range of 500 kilometres (300 miles) and could potentially be used to take out ground-based radar and interceptors of the new NATO shield.

The Russian defence ministry's announcement had prompted concern from the United States as well as neighbouring Poland and the three Baltic states of Estonia, Lithuania and Latvia.