The Obama administration is seeking full partnership with Moscow to bridge ballistic missile-defence differences that have strained US-Russian ties for years, the head of the Pentagon's Missile Defence Agency said.
He made the comments as President Barack Obama works with Moscow to cut nuclear weapons and weighs whether to go ahead with Bush-era plans to base 10 interceptor missiles in Poland and an advanced radar station in the Czech Republic - plans strongly opposed by Moscow.
"The (new) approach is to lay out ideas, and not to have a fully developed plan," Army Lieutenant General Patrick O'Reilly told a group of Reuters editors and reporters, referring to missile defence discussions with Russia.
"You need to move forward at a prudent pace so that there are collaborative decisions, intermediate decisions made along the way, so that there is true partnership," he said.
Mr Obama, during a two-day visit to Russia this week, called for a fresh era in bilateral security ties focusing on mutual interests. He and Russian President Dmitri Medvedev agreed to pursue a plan, first floated in the 1990s, to open a "Joint Data Exchange Centre" that would become the basis for sharing information on missile launches worldwide.
Mr O'Reilly said he had not received any orders "to deviate" from expanding US missile defences into Poland and the Czech Republic, an idea Moscow for years has called a threat to Russian security.
The initiative for these sites was put forward by former President George W. Bush as a hedge against Iran. Congress has said construction of the sites may not begin until those countries' Parliaments have ratified their pacts on the projects with Washington.
Mr O'Reilly said it would take up to five years for a missile field to be built in Poland and four-and-a-half years for the radar in the Czech Republic. These timelines are important because US intelligence estimates Iran may be able to fire a long-range missile possibly tipped with a chemical, biological or nuclear warhead by 2015 or so.
Neither Poland nor the Czech Republic is expected to go ahead with ratification until they get a clear signal from the Obama Administration that it is sticking with the Bush-era plan. The administration is studying possible alternatives as part of a broader missile defence review due to be completed in December, said Mr O'Reilly.
"At this point, they're still laying out alternatives," he said. "Really, it's pre-decisional."
Mr O'Reilly, who was recently in Moscow for missile-defence talks, said Russia was now seeing more eye to eye with the US on the perceived danger from Iranian and North Korean progress in ballistic missile development.
"I think there was agreement on the facts, but disagreement on the interpretation of the data or the intent" previously, he said. "And as North Korea and Iran continue to demonstrate capability, those controversies are being eliminated."
In addition, the Obama-Medvedev "endorsement" of missile-defence cooperation could be pivotal, added Mr O'Reilly, who is responsible for developing the anti-missile shield that Bush began to deploy in 2004. Mr Bush had also sought Russian cooperation on the missile shield.
Russian-US cooperation may have been hampered in the past by a perception that "we had already figured out exactly what we wanted from them and from us, and that we were going to go over there and convince them that our idea was a good one," Mr O'Reilly said.