The US has invited Russia to join its planned missile defence as an 'equal partner'.
A White House spokesman at the G8 Summit played down a warning from Moscow that it might react militarily to the US system.
Washington says it needs to base interceptor missiles in Europe to form a shield to stop possible attacks by states like Iran or North Korea.
Gordon Johndroe said: 'We want to design a system between the United States, Russia and Europe, with everyone participating as equal partners.'
US President George W Bush and Russian President Dmitry Medvedev clashed on the controversial plan on Monday, in their first face-to-face talks since the Russian leader took office in May.
Russia warned Tuesday that it would react militarily if Washington erected installations on its Cold War turf, hours after US Secretary of State Condoleezza Rice signed a deal to base some components in the Czech Republic.
