Cuba's alliance with the Soviet Union was the main reason the United States viewed Castro as a security threat–a fear that was arguably vindicated during the Cuban Missile Crisis of 1962. It began after the 1952 Cuban coup d'état which placed Fulgencio Batista as head of state and the failed mass strike in opposition that followed. After failing to contest Batista in court, Fidel Castro organized an armed attack on the Cuban military's Moncada Barracks on July 26th, 1953.