The USSR proposed a joint US project to build a dam across the Bering Strait!

The Bering Strait is the body of water between the easternmost point of Russia and Cape Prince of Wales, Alaska. In the 1950s, the Soviets proposed a dam across this strait that would warm the Arctic Ocean. The 55-mile wide dam would stop ice flows from entering the Pacific Ocean. And warmer waters would be pumped into the Arctic Ocean in an effort to change the northern climate.

A 2,000,000 kilowatt atomic power station would power this dam. The Soviets believed this dam would break the grip of the Arctic Ocean and transform the climates of Northern Asia, America and Northeast Europe. When American scientists analyzed this project, they found that it would cost an astronomical amount and was just not practicable.

They didn't believe that any of the involved countries were seriously considering the dam. They also thought that Soviet scientists were merely using the idea of this dam for propaganda purposes.

(Source)