Joint Security Area - Ending Explained

The film's ultimate tragedy is the revelation that Sergeant Lee Soo-hyeok, despite his deep affection for Jeong Woo-jin, was the one who fired the first shot that killed him. During the Mexican standoff in the North Korean bunker, a momentary panic caused by a North Korean officer's entry led Lee to fire his weapon out of a deep-seated military reflex. This truth is revealed to Lee by Sophie Jean at the end. Unable to live with the fact that he murdered his 'brother' and caused the suicide attempt of his comrade Private Nam, Lee steals a pistol and commits suicide. The final shot—the freeze-frame of the four soldiers in the same frame—reveals that they were all present at the same border post at once, a fleeting moment of peace that history would never record.

Some critics interpret the film as a political allegory for the failure of the Sunshine Policy, suggesting that individual goodwill is ultimately powerless against the institutionalized hatred of the two states. Another reading focuses on Major Sophie Jean as a surrogate for the audience; her mixed heritage and 'neutral' status reflect the modern Korean diaspora's disconnect from the raw trauma of the war, trying to piece together a history that is being actively suppressed by both governments.