On July 27, 1953, an armistice took effect, pausing the Korean War. Although much has changed over the last 70 years—North Korea becoming a nuclear state, South Korea becoming a democracy and major economic power, and China becoming Asia’s dominant force—the war remains frozen. Today, escalating tensions, including a shift in the U.S.-South Korea alliance toward competition with China, are creating new challenges to peace and stability on the Korean peninsula. As the Korean War armistice turns 70, how can the United States best prevent conflict and preserve peace?