The Department of Defense uses a decades-old nuclear system, according to a 2016 report by the Government Accountability Office.
President Donald Trump has sent a Naval strike group toward the Korean Peninsula as the threat of a North Korean nuclear test looms.
A California laboratory has begun releasing never-before-seen footage of nuclear weapons tests previously hidden by the U.S. government.
The "clock" is now at two and a half minutes to midnight, 30 seconds closer than in 2016.
President-elect also tells The Times of London he's eager to complete a trade deal with the U.K.
North Korean leader Kim Jong Un said that the isolated, nuclear-capable country was close to test-launching an intercontinental ballistic missile (ICBM).
U.S. and South Korean officials believe Pyongyang has developed nuclear weapons that threaten Japan and South Korea.
Some experts say the likelihood of another test has increased after a failed missile launch on Friday.
Recent Trump comments show he doesn't 'know much about foreign policy,' the president says.
South Korea said the exercises would be the largest ever following the North's nuclear and rocket tests.
North Korea sparked alarm after testing a hydrogen bomb last month.
Criminal gangs are exploiting poor relations between Russia and the West.
A nuclear war would be so devastating, any attempts to survive it would be futile.
Army General Curtis Scaparrotti said the country probably had access to the expertise needed to miniaturize and mount an atomic weapon on a missile.