Hidden behind a fake Howard Hughes mining venture, the CIA built a 600-foot ship to silently lift a sunken Soviet nuclear submarine off the seafloor — and decades later, parts of what it pulled up remain secret. This is not a thriller plot. It is Project Azorian, and the broad outline is now confirmed by the CIA's own declassified internal history, released in 2010.

Here is what happened. In March 1968 a Soviet diesel-electric ballistic-missile submarine, K-129, sank in the Pacific north of Hawaii, carrying nuclear torpedoes and nuclear-armed missiles, along with cryptographic gear. The Soviet Navy searched and failed to find it. U.S. underwater listening systems had logged the event, and the U.S. Navy, using the deep-sea search ship USS Halibut and towed cameras, located the wreck more than three miles down — far deeper than any salvage had ever reached. To Washington, an intact Soviet missile sub on the seafloor was an intelligence prize almost beyond price: warheads, missile design, and above all the codebooks and crypto machines that might unlock Soviet naval communications.

The plan the CIA settled on was audacious to the point of absurdity. Rather than send submersibles to pick over the wreck, they would build a ship to reach down three miles with an enormous mechanical capture vehicle — nicknamed 'Clementine,' the claw — grab the broken hull, and haul it up into the belly of the ship through doors in the bottom, all in the open ocean, in secret. To explain the construction of a bizarre, purpose-built 600-foot vessel with a derrick and a 'moon pool,' the Agency recruited reclusive billionaire Howard Hughes, whose name and reputation for eccentric, secretive ventures made the perfect screen. The ship was christened the Hughes Glomar Explorer and announced to the world as a pioneering deep-sea manganese-nodule mining vessel. An entire fake commercial industry was conjured to sell the lie.

The documentary proof is unusually rich for a black operation. In 2010 the CIA declassified a long article from its in-house journal Studies in Intelligence detailing Azorian's conception and execution; the National Security Archive at George Washington University obtained and published it. State Department and White House records, also declassified, capture President Ford and his cabinet reacting in 1975 to press leaks. And the operation accidentally birthed a piece of American legal language: when journalists filed Freedom of Information Act requests about the Agency's efforts to suppress the story, the CIA refused to 'confirm nor deny' the existence of responsive records — the now-famous 'Glomar response,' which courts upheld and which agencies invoke to this day.

Now the skeptical-but-fair reading, because the legend has grown taller than the facts. The popular version says the CIA lifted an entire Soviet nuclear submarine. The declassified history says otherwise: during the 1974 recovery, as the captured section was being raised, part of the claw failed and a large portion of the hull broke away and fell back to the abyss. The Agency recovered a section of the submarine — and with it, reportedly, the remains of Soviet sailors, who were later given a burial at sea, footage of which the U.S. quietly handed to Russia after the Cold War. What was actually retrieved in terms of intelligence — whether the prized code materials and a nuclear warhead were among it — is precisely the part that is still largely classified. The most valuable claims are also the least verifiable, by design.

The whole thing came apart not on the seafloor but in the newsroom. In 1975 columnist Jack Anderson and reporter Seymour Hersh, working from leaks, exposed the operation, blowing the cover and effectively ending plans for a second recovery attempt. The Glomar Explorer, an $800-million-class ship built for a single impossible heist, drifted into mothballs and was eventually, fittingly, repurposed for actual deep-sea drilling before being scrapped.

So the unresolved questions are not whether it happened — it did — but what it yielded. Did the CIA get the Soviet naval codes? A nuclear warhead? How much of K-129 came up, and how much intelligence value did the broken claw cost? More than fifty years on, the United States still declines to fully say, and the Glomar response it invented for this very mission remains the government's preferred way of telling you that the answer exists, and that you can't have it.