Both sides appear to want to use progress on arms control as a pathway into possible agreement on other, far trickier issues like Iran and the tiny country of Georgia, a former Soviet republic. Those difficulties and many others have pushed ties between Moscow and Washington to depths not seen in more than two decades.

Mr Obama arrives in Russia this afternoon, the first stop on a week-long trip that will also take him to Italy and Ghana. His top assistant on Russia, Michael McFaul, said in a pre-summit briefing, ''It's not, in our view, a zero-sum game, that if it's two points for Russia it's negative two for us, but there are ways that we can cooperate to advance our interests and, at the same time, do things with the Russians that are good for them as well.''

He seemed to be of one mind with the Russian leader, Dmitry Medvedev. ''Russia and America need new, common, mutually beneficial projects in business, science and culture,'' Mr Medvedev said in a internet address. ''I hope that this sincere desire to open a new chapter in Russian-American cooperation will be brought into fruition.''

Two things appear certain to be on the agenda. First, the Russians have said they will agree to allow the United States to use their territory and air space to move munitions and arms to US and NATO forces fighting Taliban Islamic extremists in Afghanistan. The Kremlin announced the deal three days before the summit as a significant sweetener for Mr Obama.

Second, a directive by both presidents for negotiators to work on a nuclear agreement that would further reduce warheads and replace the 1991 START I accord that expires on December 5. Both sides are agreed in principle to cut warheads from more than 2000 each to as low as 1500 apiece.

While Mr Obama's star power is generating buzz here, the enthusiasm doesn't extend to Russian feelings about how he's doing as president. In fact, a series of recent polls show that most Russians are sceptical of the new US leader and remain wary of the US.