This strikes me as quite sensible. Throughout the latter part of the Bush Administration, relationships with Russia were strained as the U.S. announced plans to install missile defense systems, ostensibly to protect Europe from Iranian attack, in Poland and the Czech Republic. Russia countered the move, offering to install a jointly operated missile defense systems in their own territories, but were rebuked by the Bush Administration.
The news today that the Obama Administration reportedly suggested they would be willing to abandon the missile system if the Russians can assert their significant influence and stop the purported Iranian nuclear weapon development. From the NY Times:
The officials who described the contents of the message requested anonymity because it has not been made public. While they said it did not offer a direct quid pro quo, the letter was intended to give Moscow an incentive to join the United States in a common front against Iran. Russia’s military, diplomatic and commercial ties to Tehran give it some influence there, but it has often resisted Washington’s hard line against Iran.
“It’s almost saying to them, put up or shut up,” said a senior administration official. “It’s not that the Russians get to say, ‘We’ll try and therefore you have to suspend.’ It says the threat has to go away.”
Among other things, the letter discussed talks to extend a strategic arms treaty expiring this year and cooperation in opening supply routes to Afghanistan.
It's simple quid pro quo. The Russians are tight with the Iranians and can assert far greater influence than we're able. And if the Iranians become more transparent in their nuclear intentions, the threat goes away as does the need for the (very expensive) missile shield sytems that put a wedge between Russia and the U.S.
Quite sensible.