Sept. 16, 1961 - The United States and the Soviet Union detonated nuclear devices today. Both were announced in Washington by the Atomic Energy Commission. The U.S. test, the second in two days, was again fired underground in Nevada. It was described as being of "low yield." The Soviet test was fired in the atmosphere at Novaya Zemlya, a Siberian test center, and was the 11th since Moscow broke the 3-year-old unofficial moratorium on nuclear tests. Like the others, it was fired in the atmosphere and will produce radioactive fallout. The underground tests fired by the U.S. will not.