We will respond, and it wonâ€™t just be a diplomatic protest.
That is the warning from Russia after the US and Poland signed an agreement on the controversial American missile defence shield.
Moscow has fiercely opposed the plan to base part of the shield in Poland and the Czech Republic, claiming it will change the balance of power in the region.
Vyacheslav Nikonov, an analyst at the Politika foundation, which is close to the Kremlin, said: â€œAll the talk from Washington, that the deployment of this shield in the Czech Republic and Poland is to defend Europe from Iranâ€™s nuclear programme, is nothing but a smokescreen.
â€œNow we can see that this is a response to Russiaâ€™s actions in South Ossetia. And this proves that all the components of this shield system deployed in the Czech Republic and Poland are targeting the Russian Federation.â€
Washington has insisted that Moscow has nothing to fear from the shield, arguing that it is only intended to thwart attacks from rogue states and the likes of al Qaeda.
The US plans to install ten interceptor rockets in Poland and a radar station in the Czech Republic.