Both sides appear to want to use progress on arms control as a pathway to possible agreement on trickier issues, including Iran and Georgia, the tiny former Soviet republic. Those difficulties and others have soured a promising linkage in the first years after the Cold War and pushed ties between Moscow and Washington to depths unseen in more than two decades.

In advance of Obama's arrival, a White House official told reporters yesterday that the presidents expect to announce progress on negotiations that could lead to a treaty to replace the START I agreement, which expires Dec. 5.

More broadly, the United States wants to use the summit to overhaul the U.S.-Russian relationship.

Medvedev said in an Internet address that the two powers "need new, common, mutually beneficial projects in business, science and culture.

He added, "I hope that this sincere desire to open a new chapter in Russian-American cooperation will be brought into fruition."

Two things appear certain:

* 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 U.S. and NATO forces fighting Taliban Islamic extremists in Afghanistan. The Kremlin announced the deal days before the summit as a sweetener for Obama.

* A directive for negotiators to work toward a START I replacement. Both sides are agreed in principle to cut warheads from more than 2,000 each to as low as 1,500 apiece.