Some of the fired probationary employees included on-the-ground staff at facilities where nuclear weapons are built.

The National Nuclear Security Administration is a semi-autonomous agency within the Department of Energy that oversees the U.S. stockpile of thousands of nuclear weapons. Officials were given hours to fire hundreds of employees.

U.S. President Donald Trump said on Thursday he would like to have conversations with both Russian President Vladimir Putin and Chinese President Xi Jinping about imposing limits on their nuclear arsenals.