Dr Tong Zhao is a senior fellow in the Nuclear Policy Program at the Carnegie Endowment for International Peace. His research focuses on strategic security issues, such as nuclear weapons policy, deterrence, arms control, nonproliferation, missile defense, hypersonic weapons, and China’s security and foreign policy. He is the author of “Tides of Change: China’s Nuclear Ballistic Missile Submarines and Strategic Stability” and “Narrowing the U.S.-China Gap on Missile Defense: How to Help Forestall a Nuclear Arms Race.”