The United States urged Russia on Wednesday to join its planned missile defence as "equal partners" and played down a warning from Moscow that it might react militarily to the system.
"We seek strategic cooperation on preventing missiles from rogue nations like Iran from threatening our friends and allies," said White House spokesman Gordon Johndroe. "We will continue to have a dialogue with the Russians."
"We want to design a system between the United States, Russia and Europe, with everyone participating as equal partners," Johndroe said on the margins of a rich nations summit at this mountain resort in northern Japan.
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.
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.
And 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.
"If a US strategic anti-missile shield is deployed near our borders, we will be forced to react not in a diplomatic fashion but with military resources," a Russian foreign office statement said.
"There is no doubt that the grouping of elements of the strategic US arsenal faced towards Russian territory" could lead Moscow to "take adequate measures to face the threats to its national security," it added.
Chief Bush spokeswoman Dana Perino later all but dismissed the warning, saying that Medvedev had pledged continued dialogue on the issue and strongly suggesting that the Russian ministry was at odds with its president.
"I wouldn't say we don't take it seriously, but I think that what's more important is what President Bush and President Medvedev said together here that there is a desire to work together in a cooperative effort," she said.
"Feelings that run deep like that don't necessarily change overnight," Perino told reporters, adding that "comments from that ministry have been similar in the past."
Bush told Medvedev that Washington wanted to work with Europe and Russia "on a joint partnership where we would be designing a system together and we would be working as equal partners."
The deal with Prague permits a tracking radar station and American troops on Czech soil.
The United States also wants a radar system twinned with interceptor missiles in neighbouring Poland, although negotiations with Warsaw have become bogged down with Polish demands for additional security guarantees.
"Our concept for a missile defence system is not aimed at Russia. The president repeated that to President Medvedev," said Perino, adding that Moscow's missile arsenal "absolutely dwarfed" the defensive system.
Some US officials, however, say privately that Moscow is more worried about the radar system, fearing that it could be pointed into Russia for intelligence-gathering purposes.
Former Soviet state Lithuania has offered itself as an alternative site should the Polish talks stall.
