The Voronezh-class radar comes as Russia overhauls its missile defenses in part because of what state-run news service RIA Novosti calls "new strategic challenges" posed by the U.S.-led missile shield plans in Europe.
The Voronezh-class radars are more advanced than previous Dnepr- and Daryal-class radars.
The radar in the St. Petersburg area was built in 2006 and had operated on a test basis until recently, said Col. Alexei Zolotukhin, spokesman for the missile defense troops in the Russian Defense Ministry
Two other Voronezh-class radars are operating in a test mode in Armavir in the Black Sea area and in Pionersky near Kaliningrad. Another in the Siberian city of Irkutsk will operate in test mode later this year.
Under a national defense plan extending through 2020, the Defense Ministry is to replace all Soviet long-range radars and close all gaps in radar coverage on Russia's borders.