Russia has named Sergei Kislyak, who has been the country's point man in the heated dispute over U.S. missile shields, as the new ambassador to Washington.
Kislyak, a deputy foreign minister, also has led Russia's delegation of the so-called "sextet" that is seeking resolution of the tensions over Iran's alleged intentions to develop nuclear weapons.
By leading talks with the U.S. over missile defense, Kislyak has been at the center of one of the most divisive issues between Moscow and Washington of the post-Soviet era. Russia vehemently opposes U.S. plans to place elements of a missile defense system in Poland and the Czech Republic, and has threatened an unspecified military response if the plans go through.
Russia announced the appointment Tuesday.