After years of silence, Russia has acknowledged that one of the boldest American spy missions of the Cold War succeeded in recovering two nuclear warheads from a Soviet submarine that had exploded and sunk in Pacific waters more than three miles deep.
It is the first time Russia has said that the West captured any of its nuclear arms.
The warheads were recovered in 1974 by an American vessel, the Glomar Explorer, a panel of Russian scientists said in a report to President Boris Yeltsin.
The basis for the statement was not given by the report's authors, who simply say it is of Russian origin. Some Western experts suggested that the Russians might have based the statement on Western news reports. But a former top intelligence official who has spoken to the Russians about the submarine recovery said he thought the new data were Russian.
The Glomar Explorer's attempt to recover the Soviet submarine with a giant robotic claw was widely publicized in 1975 and 1976 after the American vessel, which had been built by the CIA, lost its cover as a mining ship.
But what the half-billion-dollar venture accomplished was murky. Some accounts said the whole diesel-powered submarine had been recovered from the sea floor 750 miles northwest of Hawaii, where it sank in 1968, including nuclear warheads and code books. Others said the Glomar Explorer's huge claw had broken and dropped most of the sub and its military secrets. In an article on Dec. 9, 1976, the New York Times quoted two men who had worked on the mission as saying that two nuclear torpedoes had been recovered from the sub.
Last year the CIA disclosed that it had recovered and subsequently buried at sea six of 86 crewmen said to have been aboard the sub.
Now, a team of Russian scientists working for Yeltsin has addressed the spy mission as part of an inventory of Russian nuclear materials lost or dumped at sea. The report says the Soviet submarine, a Golf-2 class vessel, went down with 1,000 curies of radiation in the form of nuclear warheads, and that 400 curies of that were later removed.
"Bow section with NWHs," the report says, referring to nuclear warheads, "raised in August 1974 by Glomar Explorer."
The bow section of the submarine would have carried torpedoes with nuclear warheads. The rest of the Soviet vessel, which apparently slipped away when the recovery claw failed, is said to have held the sub's code room and three long-range missiles tipped with nuclear warheads.
A CIA spokesman said the agency would have no comment on the Russian report, which appears to be the first in which Moscow has addressed the outcome of the top-secret endeavor.
U.S. experts said the recovery was an intelligence coup. "It would have been very interesting to get their warheads," said Dr. Theodore Taylor, a former nuclear arms designer at the Los Alamos National Laboratory in New Mexico. "Bombs can be very different from one another. There's a good chance Soviet weaponry held big surprises for us."
William Colby, a former director of central intelligence who oversaw the Glomar Explorer's mission, praised the recovery effort in an interview and said "there's no question" that raising the Soviet submarine was a worthwhile objective. But he declined to say whether any nuclear warheads had been recovered.
Russia has become extraordinarily open about nuclear materials that it has lost or dumped at sea because, in the eyes of some Western analysts, it wants financial help cleaning them up.
"The report has been motivated by a realization of the scope of the problem and a realization that they're going to have to have international assistance to deal with it," said Sen. Ted Stevens, R-Alaska.