Operation Broken Reed : Truman's secret North Korean spy mission that averted World War III / Arthur L. Boyd.

Enhanced descriptions from Syndetics:

At the height of the Korean War, President Truman launched one of the most important intelligence - gathering operations in history. So valuable were the mission's findings about the North Korean-Soviet-Chinese alliance that it is no stretch to say they prevented World War III. Only one man -- sworn to secrecy for a half-century--survived Operation Broken Reed. Arthur Boyd recalls his role as cryptographer on a team of Army Rangers, Navy Frogmen, Air Force officers, and CIA operatives that posed as the captured crew of a B-29 bomber in January 1952. Given cover names and cyanide capsules in case of discovery, the men were transported by Chinese Nationalists wearing Communist uniforms across North Korea, where undercover allies delivered information about troop strengths, weaponry, and intention. Fraught with danger, the mission came apart on its last day when the Americans came under fire from Chinese forces wise to the operation. The members of Broken Reed supplied Trumanwith proof of massive Chinese and Soviet buildups and a heavy Soviet bomber group in Manchuria, fully loaded with atomic weapons. With the potential destruction of the world outlined in front of him, Truman chose not to escalate the Korean War, saving millions of lives.