The Russian and U.S. presidents signed a preliminary agreement on Monday to cut their countries'' nuclear arsenals to 1,500-1,675 operational warheads within seven years after a new arms reduction treaty comes into force.

The framework deal agreed during Kremlin talks between Dmitry Medvedev and Barack Obama during the U.S. leader''s first visit to Russia sets guidelines for a new treaty to replace the START 1 pact, due to expire in December. The two countries'' current levels are estimated at over 2,200 warheads.

"Within seven years after this treaty comes into force, and in the future, the limits for strategic delivery systems should be within the range of 500-1,100 units and for warheads linked to them within the range of 1,500-1,675 units," the framework agreement said.

Medvedev called the treaty a "basic element of our mutual security."

The document says the new treaty should be signed in the near future and would be in effect for 10 years. Russian officials earlier said it could be signed late this year or early in 2010.

Under the agreement, the two nations can only deploy warheads on their sovereign territories, and the new treaty will not cover cooperation in the sphere with third countries.