In August 1974, the United States undertook a top-secret mission that one CIA document disclosed in 2010 "ranks in the forefront of imaginative and bold operations undertaken in the long history of intelligence collection."

As the declassified article in the internal CIA journal Studies in Intelligence explains, Project AZORIAN was a collaboration among the CIA and private marine firms to recover a sunken Soviet submarine from the depths of the Pacific Ocean some 1,500 miles northwest of Hawaii.

The Soviet G-II class ballistic missile submarine had sunk years before, killing all aboard in March 1968. It was diesel-powered, but US intelligence suspected the vessel was armed with nuclear weaponry.

If true, the US stood to learn much about its Cold War rival if it recovered the sub. It would give the US a look at Soviet weapons design, on top of other potential intelligence treasures. Fortunately for the Americans, Moscow was in the dark regarding its lost submarine's location.

Of course, the US first had to figure out how to even retrieve a 1,750-ton vessel that sat more than three miles below the ocean surface and under tremendous water pressure. The CIA's solution: a purpose-specific ship, the Hughes Glomar Explorer, which would lug the submarine upward with a giant eight-fingered claw in the style of a claw crane grabbing a plush toy.

Global Marine and other companies agreed to conceal the ship's true function behind a cover story: The Hughes Glomar Explorer was an experimental deep-sea mining vessel, and its inauguration came complete with a champagne christening ceremony and speeches from the enterprising seafarers.

The story of the US's partial success in this long endeavor — which spanned the tenure of two presidents and three Directors of Central Intelligence — is not newly surfaced. LA Times columnist Jack Anderson broke the news as early as February 1975, and the public radio program Radiolab dedicated a half-hour program to this curious Cold War footnote (In the episode, Julia Barton reported that one of the legacies of project AZORIAN was the birth of the now-typical "neither confirm nor deny" response by government officials faced with inquiring reporters).

But what the CIA's latest disclosure does offer is several stranger-than-fiction anecdotes on the many times the Hughes Glomar Explorer's mission could have gone awry.

The submarine in question, hull number 722. Wikimedia Commons Faith in the technical viability of the project was shaky to begin with. In 1972, Admiral Moorer, Chairman of the Joint Chiefs of Staff, wrote a memo that recommended dropping the mission "because of decreased intelligence value of the target with the passage of time" and mounting costs. Deputy Secretary of Defense Kenneth Rush only estimated the project's chance of success at 20 to 30 percent.

But Director of Central Intelligence Richard Helms, the paper discloses, was worried about the long-term consequences of backing out, feeling that "a termination now would appear capricious to contractors and jeopardize future cooperative efforts."

President Nixon finally gave the project a green-light after a "long series of high-level program reviews."

After jumping these bureaucratic hurdles, the mission also had a close encounter with a major political flare-up. Too broad for the Panama Canal, the Glomar had to sail around the southern tip of South America to get the Pacific Ocean. The crew then docked in the port city of Valparaiso, Chile, only to find themselves in the midst of August Pinochet's violent coup on September 11th, 1973.

Seven technicians had traveled to Chile to join the mission. "After checking in to their hotel, early on 11 September, the Global Marine personnel were awakened by the sounds of the revolution in the streets." The Americans were under virtual house-arrest for a few days before eventually leaving safely — though not without stoking suspicions that the United States had a hand in socialist president Salvador Allende's ouster.