Russia remains suspicious about Washington's new anti-missile plans and fears its strategic nuclear weapons could still be threatened by the reconfigured scheme, the country's envoy to NATO said on Tuesday.Dmitry Rogozin's comments showed Moscow's distrust as it awaits details on Pentagon plans to create new mobile interceptor missiles, dropping an earlier U.S. scheme to set up fixed bases in Poland and the Czech Republic. "Where are the guarantees that this mobile thing, be it a boat, a cruiser, or a battleship with a mounted missile-defense system and with missile interceptors, will not sail into our northern seas?" Rogozin said at a press briefing.

By Conor Sweeney, for Reuters

Russia opposed the original U.S. plans because it did not believe assurances from Washington that they were directed at future missile launches from countries like Iran. It feared the scheme would target its own arsenal, upsetting the strategic nuclear weapons balance in Europe. Rogozin said Russia's President Dmitry Medvedev gave a guarded welcome to U.S. President Barack Obama's decision to alter the earlier Bush administration plan. But he said Moscow needed assurances it was not still the target. Under Obama's new plan, the United States would initially deploy ships with missile interceptors and in a second phase would field land-based defense systems.

A former politician, Rogozin is based in Brussels, where he represents Russia's interests at NATO headquarters, but is considered well connected within Moscow's power structures. The Pentagon says it only wants to target small and medium-range missiles from other countries, but Moscow needs convincing the system will not threaten the 3,000-plus Russian strategic warheads still pointing at U.S. and NATO countries.

Russia would be concerned if the new sea-based interceptors are based in Arctic waters, the North Sea or the Baltic Sea as this would imply that the trajectories of Russian ballistic missiles could be tracked. "We need guarantees that the parameters of deploying these anti-missile (interceptors) will in fact be restricted to small-and medium-range missiles and that they will not encroach on those territories that have serious heavy ground-based or submarine-launched ballistic missiles," Rogozin said.

The United States says the interceptors are intended to counter a potential threat from Iranian short- and medium-range missiles. U.S. intelligence now believes Iran is unlikely to have a long-range missile until between 2015 and 2020.