Last month North Korea said it conducted a hydrogen bomb test. Experts debated whether the test had actually happened but in the meantime, Senator Cory Gardner of Colorado has sponsored a North Korea sanctions bill in response to the test. The incident drew renewed attention to the danger of nuclear weapons and the Obama administration’s push to get the US Senate to ratify The Comprehensive Nuclear-Test-Ban Treaty (CTBT). The treaty is a legally binding global ban on nuclear explosive testing. The US, along with Israel, Iran, and Egypt has not ratified the treaty. Ambassador Adam M. Scheinman, the Special Representative of the President for Nuclear Nonproliferation, joins us to talk about why the US hasn’t signed onto the global treaty.