?Russia said Thursday that the U.S. approach to the deployment of a missile defense system in Europe was "unacceptable" and Moscow may stop cooperation with Washington in the missile defense field.

In a statement, the Russian Foreign Ministry slashed a recent U.S.-Spain agreement on deploying a missile defense system in Europe, saying it is unacceptable to Moscow.

The statement said the plan was not discussed collectively, nor did it take into account the positions of all the countries concerned.

The United States and Spain, two NATO members, announced Wednesday the deployment of four U.S. counter-missile ships at the Rota navy base on Spain's southwestern coast.

Russia said such a practice could negatively affect security and stability in the Euro-Atlantic region.

"If things go on the same way, then the chance to render the anti-missile defense from an issue of confrontation to an issue of cooperation, which was created at the Russia-NATO summit in Lisbon, could be lost," said the statement.

Moscow stressed that the deployment of U.S. anti-missile ships in Spain would lead to a substantial buildup of the U.S. anti-missile potential in Europe.

"We see no readiness of the (U.S.) administration to make steps toward Russia's concerns in the key issue of legally-binding guarantees that the future anti-missile system would not target Russian strategic nuclear forces. On the contrary, we detect a tendency to widen the areas of the U.S. anti-missile system deployment," the statement said.

NATO Secretary General Anders Fogh Rasmussen announced on Wednesday that Spain has agreed to host U.S. Aegis ships in Spain, and termed the deal as "an important step" for NATO's missile defense plan in Europe.

Turkey, Poland and Romania have declared their decisions to join the U.S. missile shield in Europe.

Moscow has long opposed the deployment of NATO missile defense facilities near its borders, saying they would pose a security threat to Russia and upset the strategic balance of force in Europe.

Moscow wants guarantees from the United States and NATO that the U.S.-led European missile defense shield is not targeting Russia.