Japanese Navy in the Korean War

From Geography and Japan's Strategic Choices: From Seclusion to Internationalization, by Peter J. Woolley (Potomac Books, 2005), Kindle pp. 110-111:

When the Japanese withdrew from the Korean peninsula in 1945, the allies had split Korea into north and south, allowing the Soviets to set up a Stalinist protégé to head a communist government in the north. Meanwhile, the Western allies installed a proto-constitutional regime in the south. On June 25, 1950, the Soviet-armed North surprised and quickly overran the South. The North Korean army took the capital, Seoul, in a matter of days and advanced down the peninsula in a matter of weeks. It was stopped only ninety miles from the Strait of Tsushima by U.S. and South Korean forces desperately defending the last perimeter and using Japan as their rear base of supply and air operations.

The strategic importance of Japan to the United States and vice versa seemed to crystallize. For Japan the tables had turned completely. Rather than being the strong man of Asia, bullying its way over the Asian mainland, it was prostrate at the feet of the allies, a small archipelago on the edge of a vast continent dominated by large, aggressive powers, protected only by its erstwhile rival for Pacific power, the United States. For the United States, Japan ceased to be the demon of the Pacific and was a strategically invaluable outpost on the far side of the world’s largest ocean on the edge of the Asian expanses. Indeed, the conqueror of Japan, the supreme allied commander and a student of Asian history, took a page from Japanese military history in launching the most audacious amphibious counterattack on Korea, the “dagger pointed at the heart of Japan” as it had been called a century earlier. Landing in Inchon in mid-September precisely where the Japanese had landed in 1904, MacArthur drove his forces to Seoul in ten days, cutting off North Korean troops that had overrun the length and breadth of the peninsula. His reenactment of the Japanese landing in Inchon exceeded in speed, audacity, and effectiveness any and all of the many amphibious attacks in the Pacific during the war. Vital to the plan was the proximity of Japan, which provided a rear base for troops and supplies, safe ports for naval vessels, and air fields for fighters and bombers. But Japan’s participation in this war was more than just a passive staging area for U.S. operations.

Japanese minesweepers operating now under the auspices of the Maritime Safety Agency were called into service for the United States in late 1950 to clear North Korean harbors of mines sowed by the North Koreans. The United States was woefully short of both minesweepers and experienced crews, and the deficit could not be made up by any of the other fourteen UN member nations taking part in the fight. In fact, “there was only one expertly trained and large minesweeping force in the world qualified to do the job, the forces of the Maritime Safety Agency.” Unbeknownst to the Japanese public at the time, Japanese crews operated in foreign waters, in a war zone, against an undeclared enemy regardless of Article 9 of the constitution.

I first heard about Japanese minesweepers from two grizzled characters, one very talkative, the other very taciturn, whom we met on a beach in Tsuruga in 2011. The taciturn man had been a Japanese Navy captain in command of a minesweeper recruited by the U.S. Navy, according to his loquacious companion. That's where I learned the Japanese word for 'naval mine': 魚雷 gyorai lit. 'fish-thunder', which more commonly refers to torpedoes, as in 魚雷艇 gyoraitei 'torpedo boat'. (Torpedoes are also called "fish" in anglophone sailor slang.)