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5,000 Meters Deep: The Cold War's Lost Thermonuclear Bomb in the Philippine Sea
In 1965, a US Navy A-4E Skyhawk carrying a B43 thermonuclear bomb rolled off the USS Ticonderoga and sank in the Philippine Sea. The pilot, plane, and bomb were never recovered and now rest 16,000 feet deep, a secret held from the public until 1989.
In the vast, crushing darkness of the Philippine Sea, nearly 16,000 feet below the surface, lies a chilling relic of the Cold War. It is not a shipwreck of ancient mariners or a geological anomaly. It is a Douglas A-4E Skyhawk attack aircraft, and inside its wreckage rests a B43 thermonuclear bomb, a weapon with a potential yield over 60 times that of the one used on Hiroshima.
An Accident on the High Seas
The date was December 5, 1965. The aircraft carrier USS Ticonderoga was sailing approximately 80 miles from Kikai Island, Japan. On its deck, a routine military exercise was underway. Lieutenant (junior grade) Douglas M. Webster was in the cockpit of his A-4E Skyhawk, which was being rolled onto a hangar elevator. Suddenly, in a catastrophic failure of procedure and equipment, the aircraft began to roll off the elevator. Despite the crew's frantic efforts, the plane, its pilot, and its nuclear payload tipped over the side and plunged into the abyss. The sea swallowed them whole. The immense depth made any immediate recovery impossible, and the Skyhawk, along with Lt. Webster and the bomb, was lost.
A Secret Held for Decades
For 24 years, the incident was shrouded in secrecy. The Pentagon classified the event, and the world remained unaware that a weapon of mass destruction lay on the ocean floor. The official policy was to neither confirm nor deny the presence of nuclear weapons anywhere. It wasn't until a 1989 report prepared for the U.S. Congress was made public that the truth finally surfaced. The revelation sent a shockwave through the international community, particularly in Japan, a nation with a deeply ingrained anti-nuclear stance due to its history. The Pentagon sought to quell fears, stating officially that the loss posed no significant risk. In a declassified 1981 report, the Department of Defense concluded:
A review of the circumstances of the incident, the weapon design, and the results of other accidents involving nuclear weapons has led the Department to conclude that this weapon loss has not resulted in a hazard to human health or to the marine environment.
An Unsettling Legacy
Today, the lost bomb remains a subject of uneasy fascination and debate. Is it truly safe? The official position is that the B43 bomb was designed with multiple safety mechanisms to prevent accidental detonation. The immense pressure and cold at that depth make a nuclear yield impossible. Furthermore, its casing was built to withstand harsh conditions. However, questions linger about the long-term effects of saltwater corrosion. Could the weapon's plutonium core eventually be exposed, leaking radioactive material into the marine ecosystem? While experts deem this a low-probability, long-term risk, the thought remains deeply unsettling. The bomb resting on the seabed is a stark reminder of the hidden dangers of the Cold War—a silent, powerful monument to an era of nuclear brinkmanship and the accidents, known as "Broken Arrows," that it spawned. It lies there still, a secret the ocean was forced to keep for over two decades, and a truth we must now live with.