Attack on the Ozbourn: A Nuclear Weapons Incident During the Vietnam War

The Ozbourn on 27 or 28 March 1967; note impact points at fore and aft. Photograph taken by Michael S. Krause. From the U.S.S. Ozbourn Association website. http://www.ozbourn.org/index.htm

Recently declassified but heavily excised documents from the Lyndon B. Johnson Presidential Library suggest that a Vietnam-war skirmish involving a nuclear-armed U.S. destroyer raised questions at the White House about the presence of nuclear weapons on U.S. warships in Vietnam military operations.  That the documents are heavily excised more than forty years after the incident raises troubling questions: Why information in these documents is still classified? Could full declassification really cause any harm? What is the U.S. government afraid of?

Over a two-week period at the end of March 1967, the U.S. 3rd Marine Division, concerned about a North Vietnamese threat to an artillery base at Gio Linh, conducted an operation codenamed Beacon Hill I along the South Vietnamese coast below the Demilitarized Zone (DMZ). This effort featured the amphibious landing of a Marine battalion and the participation of Navy destroyers on a “gun line” to furnish fire support. During the first two days the Marines, pinned down by North Vietnamese fire, found their adversary had many positions with connecting tunnels, and decided to stand back while naval guns and air strikes bombarded these positions for the next two days. On the early morning of 25 March, one of the supporting ships, the Ozbourn, completed her fire mission and began to leave. Suddenly North Vietnamese mortars hit her with several shells.  Two damaged the Ozbourn’s ASROC [anti-submarine rocket] storage area, igniting rocket motors and forcing the crew to flood the magazine.  ASROCs were nuclear-capable weapons so explosions in a magazine raised the possibility, at a minimum, of radioactive materials scattering about the ship.  As it turned out, no radiation was released.[1]

The two newly declassified documents disclose that data on this incident was quickly relayed from the Pentagon to the White House, where deputy national security adviser Bromley Smith raised with security adviser Walt Rostow and senior State Department officials the problem of nuclear weapons on U.S. ships involved in Vietnam War operations. The Pentagon report and Smith’s memorandum are heavily excised but the location of the excisions shows that nuclear-armed ASROCs, rather than the conventional version, must have been involved. Even the identity of the ship is exempted but an on-line search discloses its name, the U.S.S. Ozbourn, thanks to a helpful report by Charles Bogart in a military history newsletter.[2]  While the Johnson White House was plainly concerned that word of the incident would reach the press (it never did), some of the wording suggests a more basic concern: “why” were nuclear weapons deployed on ships involved in conventional military operations, especially when such operations risked the possibility of nuclear weapons accidents.  Whether any policy changes resulted remains to be learned, but nuclear weapons were deployed on U.S. navy surface ships until the end of the Cold War.

The Ozbourn in 1964. From the U.S.S. Ozbourn Association http://www.ozbourn.org/index.htm

It is worth noting that the Ozbourn incident does not show up in the Pentagon’s official reports on nuclear weapons incidents and accidents.[3]  In an invaluable 1980 study for the Center for Defense Information’s Defense Monitor, “Nuclear Weapons Accidents: Dangers in Our Midst,” Robert S. Norris explained the Defense Department’s taxonomy for nuclear weapons accidents and incidents.  Certainly the attack on the Ozbourn was not in the worst category, NucFlash, or the next worse, Broken Arrow, involving non-nuclear detonation and radioactive contamination (think of the crashes of nuclear-armed B-52 in Spain and Greenland in 1966 and 1968).[4]  Somewhat less serious was a Bent Spear (such as the accidental movement of nuclear-armed cruise missiles on a B-52 bomber in 2007), after that is Dull Sword.  A Bent Spear must be “nuclear weapons significant incident,” while a Dull Sword is a lesser event. The risks inhering in the Ozbourn episode may put it in the Bent Spear category, even if it never made the Official Pentagon record of nuclear weapons incidents.

Here is the Ozbourn’s Deck Log Book from 25 March which describes how the ship was “taken under fire by enemy mortars off the coast of Vietnam about 4000 yards east of the demilitarized zone.”

"The ship received two direct hits causing damage in the MK25 radar room and ASROC magazine."

As long as the relevant documents are excised, it will be difficult to know how serious the consequences of the attack on the Ozbourn might have been.  Knowing whether there were only two, or perhaps three or more, nuclear warheads involved makes a difference for gauging the potential gravity of the worst case. Yet, even though the U.S. Navy removed such weapons from all surface ships 20 years ago, the U.S. government continues to use the Formerly Restricted Data category of the Atomic Energy Act to classify any information relating to historical nuclear deployments on ships or overseas territories. The Department of the Energy and the Pentagon have been the chief enforcers of the policy on historical deployments. Secrecy advocates consistently lump all information in the same category with truly sensitive information, making the protection of really important data more expensive, and ultimately more difficult.  While a basic purpose of the Atomic Energy Act was to prevent the spread of knowledge about nuclear weapons design and related sensitive technical secrets, it is perplexing why the U.S. government insists on protecting something that not only has nothing to do with nuclear proliferation but also no longer exists.   The world has moved on, but declassification has not; data about the old nuclear deployments should be in the public record.

On appeal to the Lyndon Johnson Library, the National Archives declassified the full title of the Pentagon report on the incident, so we are now sure that it involved nuclear weapons.   The appeal process is not yet played out, however, so more may be learned. Yet, without changes in the declassification rules it is unlikely that an appeal will produce much.  A forthcoming report by the Public Interest Declassification Board will suggest needed changes to the FRD system, but it will take a prolonged effort to get the Pentagon and Department of Energy to accept openness on historic nuclear deployments.