U.N. Considers a Historic Ban on Nuclear Weapons, But U.S. Leads Boycott of the Talks

Some 120 countries gathered at the United Nations this week to draft a treaty to ban nuclear weapons. But the United States is leading a boycott of the talks. Meanwhile, more than 2,000 scientists signed an open letter endorsing the U.N. talks, and, on Tuesday, Pope Francis encouraged the United Nations to pursue the "total elimination" of nuclear weapons. We speak to Zia Mian, physicist, nuclear expert and disarmament activist. He is co-director of the Program on Science and Global Security at the Woodrow Wilson School of Public and International Affairs, Princeton University.