Russia will allow the United States to ship weapons across its territory to Afghanistan, a top Kremlin aide said Friday in a gesture aimed at bolstering U.S. military operations and improving strained ties between Washington and Moscow.

The deal is expected to be signed during U.S. President Barack Obama's visit to Moscow next week, Kremlin foreign policy adviser Sergei Prikhodko said.

Russia has been allowing the United States to ship nonlethal supplies across its territory for operations in Afghanistan, and Kremlin officials had suggested further cooperation was likely.

Prikhodko told reporters that the expected deal would enable the United States to ship lethal cargo and would include shipments by air and land.

He said it was unclear whether U.S. soldiers or other personnel would be permitted to travel through Russian territory or airspace.

"They haven't asked us for it," he said.

The normal supply route to landlocked Afghanistan via Pakistan has come under repeated attack by the Taliban, and the United States and NATO have been eager to have an alternate overland supply route through Russia and a few Central Asian countries.

Confirmation of such a deal appeared aimed at setting a constructive tone for the meetings between Presidents Barack Obama and Dmitry Medvedev on Monday and Tuesday. After years of increasing strain, both governments have expressed hope that the summit will put ties between the former Cold War rivals back on track.

Serious rifts remain over other defense issues. The United States 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 United States to scrap the previous administration's plans for missile defense facilities in Eastern Europe.

The United States says missile interceptors based in Poland and a related radar in the Czech Republic would, if built, 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 on 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.