MOSCOW, April 27 (RIA Novosti) - The first round of full-format Russia-U.S. talks on a new strategic arms reduction treaty will be held on May 18-20 in Moscow, the Russian Foreign Ministry said Monday.

The Strategic Arms Reductions Treaty (START 1), signed in 1991, obliges Russia and the United States to reduce nuclear warheads to 6,000 and their delivery vehicles to 1,600 each. The treaty expires on December 5 this year.

Russian President Dmitry Medvedev said in Helsinki last week that any new deal to replace START 1 must also cover delivery systems.

Medvedev and U.S. President Barack Obama agreed at their first meeting in London earlier this month on an immediate start to talks on a new strategic arms reduction treaty.