Too many observers have lost sight of one of the key lessons of World War I. The Great War was triggered by the assassination of Austrian Archduke Franz Ferdinand in June 1914, which occurred against the backdrop of a long-simmering conflict between Europe’s major powers. This interplay between conflict escalation and a political spark has special resonance today.

With war raging in Ukraine and a cold-war mentality gripping the United States and China, there can be no mistaking the historical parallels. The world is simmering with conflict and resentment. All that is missing is a triggering e...