Oren Etzioni used to be one of those AI optimists. Now, not so much. In fact, he’s so worried about AI-manipulated content, he created a non-profit, TrueMedia.org, to help ordinary people sort AI fact from fiction.

US adversaries are on a propaganda offensive around the world. Earlier this month, the Council on Foreign Relations in DC convened a discussion about the changing landscape of disinformation campaigns with James Rubin, special envoy at the Global Engagement Center at the State Department, Jon...