Scientists at Sandia National Laboratories claim to have successfully tested an upgraded version of the B61-12 nuclear bomb.
The US has been working on the B61-12 for several years, and government officials say the latest tests are vital to refurbishing efforts.
An F-16 from Nellis Air Force Base in March successfully dropped a zero-yield version of the bomb over the Nevada desert. It left a "neat hole" and crews were able to dig it out of the dirt for further study.
Sandia Stockpile Resource Center Director Anna Schauer said, "It's great to see things all come together: the weapon design, the test preparation, the aircraft, the range and the people who made it happen."