Russia warned the United States on Wednesday that it could be inviting trouble with the latter's plan of stationing missiles sites in Europe, purportedly as a form of deterrence and defence against the growing nuclear capability of Iran.

Russian President Dmitry Medvedev called on his U.S. counterpart, President Barack Obama, to ponder deeper on his plan of establishing missile defence sites in European nations, including Poland and Romania, a spectre Medvedev said seriously troubles his government.

In any event that the U.S. and its allies within the North Atlantic Treaty Organisation (NATO) want to push ahead with the missile plans, Russia said that it would be prudent for the program to be jointly undertaken by regional leaders, with Moscow not hiding its intent to be part of the picture.

The NATO leadership, however, rejected the idea, prompting Russia to drag its feet on discussions earlier started to iron out political kinks of the U.S. plan.

In a policy speech, Mr Medvedev declared that if the U.S. and NATO insist on their unilateral designs, armed reactions coming from Moscow cannot be ruled out in the process.

"The United States and its NATO partners as of now aren't going to take our concerns about the European missile defence into account," Mr Medvedev was quoted by the Associated Press .

Basing on its outlined defence plan of thwarting Tehran's nuclear agenda, Washington calls for the installation of radar and interceptors in specific European locations over the next decade, with options of upgrading the facilities as the need arises.

Such move, according to the Russian president, will lead to retaliatory actions from Moscow, which would mean the deployment of short-range Iskander missiles in Kaliningrad in the Baltic Sea and other strategic sites.

The placements, he added, will have definitive capabilities to strike on U.S. targets and the planned missile defence sites.

Observers noted that Medvedev's latest words were so far the strongest against the West and were delivered as Russia prepares for the upcoming parliamentary elections early in December.

Also, Russia watchers are assuming that Mr Medvedev could be consolidating popular support as he prepares to slide up to the Prime Minister post once Vladimir Putin wins the presidential election next year, as widely expected by many.