NATO says its U.S.-led missile defense shield for Europe is up and running.

Secretary General Anders Fogh Rasmussen said Sunday in Chicago that the system has entered “interim capability” – with missile interceptors on a U.S. warship in the Mediterranean and a radar system in Turkey.

NATO is looking to have a defense network in place that can intercept a missile attack anywhere in Europe by the end of this decade.

Former U.S. President George W. Bush originally proposed a land-based missile defense shield to protect NATO allies from possible attack by Iran or other hostile governments. President Barack Obama later modified the plan to place some of the radar on ships.

The missile defense shield created friction between the United States and with Russia which regards it as a threat to its own security. The Kremlin has threatened to place offensive missiles on NATO's borders if the alliance's plans go forward.

Washington and NATO have invited Russian cooperation on missile defense. They say the shield does not target or threaten Russia in any way.