The Bush administration has selected the design for America's first new nuclear warhead in nearly two decades.
US officials say the warhead will not add to the country's nuclear arsenal, but will replace existing missiles.
Critics have complained it sends the wrong signal at a time when the White House is leading efforts to curb Iran and North Korea's nuclear ambitions.
The chosen design was developed in a Californian laboratory and is based on a warhead already tested in the 1980s.
The US Congress authorised design work on a new warhead in 2005 on the basis that there would not be any fresh missile tests.
No nuclear underground tests have been conducted since a ban in 1992.
The new warhead, due to be operational in five years' time, will be used to replace Trident missiles on submarines.