Mr. Stewart is senior program director and senior fellow at the Carnegie Council for Ethics in International Affairs . He is also a Truman Security fellow and an adjunct assistant professor in international affairs at Columbia University and New York University. He is the founding editor of Policy Innovations.

Mr. Stewart's writings have appeared in more than ten languages in numerous publications, including Foreign Affairs, The American Interest, Newsweek, Foreign Policy, SAIS Review, Ethics & International Affairs, The Wall Street Journal, The International Herald Tribune, Current History, The Asahi Shimbun, and The National Interest. He is a contributing author to several monographs and books, including What Do We Do about Inequality? (the Wicked Problems Collaborative, 2015), International Relations: Perspectives, Controversies, and Readings (Cengage, 2013), Reimagining Japan: The Quest for a Future That Works (Simon & Schuster, 2011), Tsunami: Japan's Post-Fukushima Future (Foreign Policy, 2011), and Energy Security Challenges for the 21st Century: A Reference Handbook (Praeger Security International, 2009).

He earned an MA at Johns Hopkins University School of Advanced International Studies (SAIS) and a BA from the University of Delaware.