The United States and other countries that engage in friendly but unofficial relations with Taiwan generally maintain “strategic ambiguity” on the question of whether they would help Taiwan defend itself against a possible armed attack by China. Their decision would undoubtedly be affected by many factors, including how the world would regard third-party intervention (especially military intervention) in a China-Taiwan conflict. Would the United Nations, and international law more generally, view third-party military intervention in a cross-Strait conflict as an illegal use of force? In this installment of our occasional speaker series, “Taiwan Legal,” Professor Julian Ku of Hofstra University School of Law will explain what international law says about the use of force for self-defense and collective self-defense.