But the invasion never came. For years,American scientists had been developing a secret weapon,the atomic bomb.

VOA: special.2011.06.23

It was built in the 1940s as part of the "Manhattan Project" to develop the first atomic weapon during World War II.

CNN: Federal funds aim to clean up nuclear wasteland

Perhaps the most spectacular failure of the United States was in misjudging how soon the former Soviet Union ended America's nuclear monopoly in August 1949 by testing its own atomic weapon.

CENTERFORSECURITYPOLICY: Questionable intelligence on Iran

The Obama administration has staunchly opposed allowing countries seeking nuclear-cooperation with the U.S. to engage in enrichment or reprocessing, because either path could be used to create the fissile material required to create an atomic weapon.

WSJ: Seoul Seeks Ability to Make Nuclear Fuel