Russia was seen as the instigator of Kyrgyzstan's decision earlier this year to evict the United States from an air base used to ship military hardware and troops to Afghanistan. The decision was reversed only after the U.S. agreed to pay three times the price.

No comment was immediately available from the Pentagon on Friday, a federal holiday.

The expected deal would be the first time Russia has allowed U.S. military shipments through its territory during the Afghan campaign, said Fyodor Lukyanov, editor of Russia in Global Affairs magazine. "This may actually be the first time they will do this since World War II," he said.

Serious rifts remain over other defense issues. The U.S. and Russia want to forge a nuclear arms reduction agreement to replace the 1991 START treaty, which expires in December.

But talks on a new treaty are complicated by Russia's push for the U.S. to scrap the previous administration's plans for missile defense facilities in Eastern Europe.

The U.S. says missile interceptors based in Poland and a related radar in the Czech Republic — if built — would be aimed to counter a potential Iranian threat and would not threaten Russia. Russia rejects those arguments and says the facilities would be aimed to weaken Russia's nuclear deterrent.

Prikhodko said Medvedev and Obama are expected to sign a declaration of understanding that would set out guidelines for a new arms reduction treaty and would likely include specific target numbers.

He insisted that plans for further nuclear arms cuts and a possible U.S. missile shield in Europe are inextricably linked and that Russia wants the Obama administration to acknowledge that. U.S. officials have rejected Russia's argument that cuts in offensive weapons must be linked with U.S. plans for missile defense.

"We would like the interconnection between START and missile defense to be described" in the declaration signed at the summit," he said.

Prime Minister Vladimir Putin's spokesman also said that the two issues are interconnected and indicated Russia's leaders would repeat their arguments in meetings with Obama, who is to hold talks with Putin as well as Medvedev.