MOSCOW, July 29 (RIA Novosti) - President Dmitry Medvedev has named Sergei Kislyak, a deputy foreign minister and Moscow's representative in Iranian nuclear talks, as Russia's new ambassador to the United States.

Kislyak, 57, who leads the Russian delegation at the six-party denuclearization talks with Iran, will replace Yury Ushakov as ambassador to the U.S. according to a presidential decree published on the Foreign Ministry's website on Tuesday.

The new ambassador is a career diplomat who has been in the Foreign Ministry since 1977. He also served as the Soviet envoy to the United Nations and the U.S. He headed the ministry's security and disarmament department from 1995-1998, and served as ambassador to Belgium and NATO from 1998-2003.

Iran's controversial nuclear program and Washington's missile defense plans for Central Europe have been major points of contention of late between Russia and the U.S., former Cold War ideological enemies.

Ushakov, who held the post for almost nine years, quit as Russia's ambassador to the U.S. in early June and joined the government staff under new Prime Minister Vladimir Putin.

Washington appointed a new ambassador to Russia, career diplomat John Beyrle, 54, in early July.