NATO leaders agreed to launch the first phase of a missile shield to protect Europe, an alliance official told AFP, despite Russian opposition to the system. The leaders "just decided" to declare an initial capability, the official said on condition of anonymity, meaning a US warship armed with interceptors and a radar system based in Turkey will come under NATO command at a German base. The alliance insists the shield is not aimed at Russia and aims to knock out missiles that could be launched by enemies such as Iran. But Moscow, fearing that the system will also serve to neutralize its nuclear deterrent, has threatened to deploy rockets to Kaliningrad exclave near Poland in response to the shield. In a bid to appease its former Cold War foe, the Western military alliance invited Russia to cooperate in the system at the last summit in November 2010 in Lisbon, but the two sides have struggled to find common ground. "This is not a project targeted against Russia, but a project we want to push forward with Russia in the interest of Europe's security," said German Foreign Minister Guido Westerwelle. "And therefore the door for Russia will stay open." Russian President Vladimir Putin declined to attend the NATO summit in US President Barack Obama's adopted hometown. Moscow has called for joint control over the system and for NATO to sign a legally-binding guarantee that it is not aimed at Russia. But NATO has balked at both demands, insisting on keeping two separate systems and refusing to sign a legally-binding document. The system is scheduled to be deployed in four phases and become fully operational by 2018. Spain will host four US Aegis ships at its port in Rota while Poland and Romania have agreed to host US land-based SM-3 missiles in the coming years.