As a candidate, President Trump asked, "If we don't use nuclear weapons, why do we have them?" "Modernization" began with Barack Obama. Now, it's more intense than at any time since the Cold War, which ended when Ronald Reagan and Michael Gorbachev agreed to downsize their arsenals. India, Pakistan — even North Korea — have programs for nuclear weapons, the US is buying new ones — and B-52s may go back on 24-hour alert. We hear about the benefits of the new strategy and the risks. Is it required by new realities, or a return to "nuclear madness?"