Editor's Note: The following is part two of a three-part series on economic espionage; part one may be accessed here . Following World War II, the United States firmly established itself as a global political and industrial power. With the fall of the Soviet Union in 1991, it became the world's sole superpower. This ascent has made the United States the preeminent target for industrial espionage in the early 21st century by the main countries that seek to undermine its relative power, Russia and China. The Soviet Union/Russia At the midway point of the 20th century, the Soviet Union presented the clearest espionage threat to the United States. It had just detonated its own atomic bomb in 1949 that ended the four-year U.S. monopoly on nuclear weapons, largely thanks to comprehensive Soviet spying on the Manhattan Project.