At the height of the Cold War, the world's two superpowers created a new pair of battlefield aircraft, similar in both power and purpose. One was the U.S.'s revered A-10 Thunderbolt II, also known affectionately as the Warthog. Its Soviet cousin, originally revealed in 1981, was the Sukhoi Su-25 Grach. While the Soviet call sign "Grach" means "rook," the USSR's adversary NATO gave the Su-25 a much less imposing designation: the "Frogfoot." The A-10 has become a legend—an iconic aircraft that can change the course of a battle with a strafing blast of its 30mm GAU-8 cannon, and fights on...