Today, the latest agreement shackling the nuclear arsenals of Russia and the US is set to expire.

The New START Treaty, signed in 2010 by former US President Barack Obama and then-Russian President Dmitry Medvedev capped how many nuclear weapons each side could deploy.

But with no replacement deal in place, those restrictions are disappearing opening the door for both Washington and Moscow to rapidly build up their nuclear forces.

• Guest: Daryl Kimball, Executive Director of the Arms Control Association
• Producer: Tyler Hall