The expiration of the last remaining nuclear treaty between the United States and Russia on Thursday has sparked fears about a nuclear arms race, with the two biggest nuclear superpowers without ...

NPR's Mary Louise Kelly speaks with Christine E. Wormuth of the Nuclear Threat Initiative about the state of a potential nuclear arms race now that the current nuclear-arms-control treaty has expired.

For the first time in half *** century, limits on the world's largest nuclear arsenals could be lifted if *** pact between Russia and the United States is allowed to expire. Experts fear that could ...

Add Yahoo as a preferred source to see more of our stories on Google. US President Donald Trump, left, and Russian President Vladimir Putin. - Getty Images The expiration of the last remaining nuclear ...