The Plot to Drop a Nuclear Bomb on Imperial Japan’s Navy

Steve Weintz

Security, Asia

When the Manhattan Project got off the ground in 1943, both the atomic bomb and the defeat of Japan looked like a long time and a lot of work away.

The great bombings left the lagoons of both Bikini and Chuuk littered with shipwrecks. Nature has miraculously restored their waters and made the sunken fleets among the greatest diving destinations in the world. Despite the thriving population and a developing economy, Chuuk Lagoon remains a wonderland of sea life and corals grown up over the corpses of warships, transports, trucks and planes.

Less than a year after the formal end of World War II the United States tested its new superweapons in peacetime. Operation Crossroads in 1946 at Bikini Atoll tested the effects of nuclear weapons on naval fleets and harbors.

While burrowing through the vast Manhattan Project archives historian Alex Wellerstein turned up evidence that Bikini wasn’t the first Pacific island in the atomic crosshairs. Another atoll may have been the earliest target considered by the Manhattan Project.

For a time before the bombings of Hiroshima and Nagasaki, the United States considered nuking the Japanese fleet at anchor — a kind of reverse, radioactive Pearl Harbor.

When the Manhattan Project got off the ground in 1943, both the atomic bomb and the defeat of Japan looked like a long time and a lot of work away.

Hard fighting that year in New Guinea, Bougainville, the Solomons and Tarawa showed just how much time and work. But U.S. Navy planners thought the biggest target and the hardest nut in the Pacific was the huge Japanese naval base at the remote Micronesian atoll of Chuuk, once known as Truk.

After ruling Micronesia for a quarter century, the Japanese navy had turned Chuuk into its own version of Pearl Harbor.

The atoll — a 40-mile-wide lagoon ringed and dotted with tall green tropical islands — sheltered everything from battleships to transports. Drydocks and tank farms supported the ships. Airfields serviced hundreds of planes. A fleet radio station reached across the entire Japanese island frontier.

The carriers that fought in the Coral Sea and the battlewagons that savaged Guadalcanal came from Chuuk.

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