CNN

MOSCOW, Russia (CNN) – Russia will allow the United States to ship weapons across its air space to Afghanistan, Kremlin spokesman Alex Pavlov said Friday.

Pavlov said he doesn't know when the policy will take effect, but imagines the details will come out when presidents Barack Obama and Dmitry Medvedev meet Monday and Tuesday in Moscow.

A senior official in the Obama administration told CNN the men are expected to sign an agreement to allow the transit of U.S. military equipment to Afghanistan for use in American military operations.

The two countries already have an agreement allowing rail transportation of non-lethal supplies across Russian territory.

On Thursday, Medvedev said Obama's new administration has shown a willingness to "build more effective, reliable, and ultimately more modern relations. We are ready to play our part."