Department spokeswoman Victoria Nuland told reporters there were senior-level diplomatic talks with Moscow in late 2012 on the antimissile issue.
The Obama administration for years has expressed interest in collaborating with Russia in specific areas of missile defense such as sharing radar data on threats. The Kremlin, though, has balked at any deal that does not also address its concerns that advanced U.S. missile interceptors planned for fielding in Europe in the coming years could threaten Russian strategic nuclear weapons.
"We remain committed to cooperating with Russia on missile defense," Nuland said. "We think this can be a win-win for both of us because we think we share the same threats. But it’s going to require Russia being willing to have a real conversation about how we can work together on this, and that’s been difficult."
An expected summit between Presidents Obama and Vladimir Putin in the first half of 2013 is likely to address missile defense.