Russia does not ruled out countering the US missile defense shield in Europe with Iskander-M missile systems, should Washington proceeds with its deployment.

"If we cannot agree on this question (missile defense), then you know the consequences," said Russian President Dmitry Medvedev Friday, after a summit of the Group of Eight industrialized nations (G8) in the central Italian city of L'Aquila, reports AFP.

Moscow has threatened to install the potent systems in Kaliningrad, a Russian exclave near Poland which together with the Czech Republic is expected to host elements of the US shield.

"I have nothing to add, and what I said in my address to the nation remains valid," said Medvedev, referring to a late 2008 speech in which he had introduced the possible Russian response.

The plans, inherited from the former US administration, threaten to upset the two sides' recent attempts at a rapprochement.

Neither side, however, has agreed to change its argument on the move with Russia denouncing it as a 'security threat', and Washington insisting that it provides defense against "rogue states".

HN/MB/MMN