President Hamid Karzai''s office said Monday that Russia is ready to cooperate on defense matters with Afghanistan. The announcement coincides with an increasingly public tussle between Afghan and Western officials.

Russia''s President Dmitry Medvedev told Karzai in a letter that cooperation on defense issues would "be effective for both countries and also effective for maintaining security in the region," Karzai''s office said in a statement.

"As a friendly government to Afghanistan, Russia is ready to offer its cooperation to an independent and a democratic Afghanistan," the statement quoted Medvedev as saying.

The statement did not say how the two countries would cooperate.

A spokesman at the Kremlin in Russia said he did not immediately have any details about the exchange between Medvedev and Karzai.

Moscow would have little to gain if the U.S. and NATO mission to defeat the Taliban and install a strong central Afghan government failed. The relationship between NATO and Russia has been delicate for years, but Russia in November allowed Spain and Germany to use Russian rail lines to ship supplies for their forces in Afghanistan.

The correspondence from Karzai — on the eve of U.S. President-elect Barack Obama''s inauguration — comes as Afghan officials are fighting criticism that Karzai''s government is weak and corrupt.