Restricted Data: The History of Nuclear Secrecy in the United States is based on a decade of archival research, using dozens of archival collections to construct a synthetic narrative of a vast, still-secret history. Below are some of the more significant, interesting, and amusing documents unearthed as part of this investigation. One may also be interested in the Document List at Restricted Data: The Nuclear Secrecy Blog.
Note that the documents collected on these pages were done exclusively for the purposes of research. Some are based on microfilm scans, which have very high contrast and can frequently obscure text. Others are photographs quickly taken with a digital camera in an archive, where the lighting sources are unideal. As a result, the reproduction quality can vary, but it does give the reader a sense of what the historian’s job looks like.
Letter by Vannevar Bush about scientists and security clearances, February 1942
Vannevar Bush to R.H. Thayer (28 February 1942), Bush-Conant File Relating the Development of the Atomic Bomb, 1940-1945, Records of the Office of Scientific Research and Development, Record Group 227, microfilm publication M1392, Washington, DC: National Archives and Records Administration, n.d. (ca. 1990) Roll 3, Target 2, Folder 15, "S-1 OSRD Research Program, Executive Planning Committee (Fldr.) No. 1 (1941-42)."
In early 1942, Vannevar Bush (head of the Office of Scientific Research and Development, the organization that was at that point in charge of research into uranium fission), got notice from the Navy that they were not willing to give one of the main scientists working on fission, Arthur H. Compton, a security clearance. This was on account of the fact that Compton had signed some petitions over the years that they considered to be indicative of too-radical politics. Bush's reply to Lt. Commander R.H. Thayer, overriding the Navy's veto, is a fascinating one. He explains that this particular project had a "special status" because of both its importance and because there was already considerable speculation about it in the popular and scientific press. As a result, it could not really be kept as secret as they would like, but scientists who were possibly security risks perhaps ought to be taken into the work anyway, and put under a secrecy oath and observation, as a means of tamping down their ability to spread more information. "In fact," Bush concluded, "I am inclined to believe that should the subject become at all imminent in the sense of promising practical results within a reasonable interval it would be well to take in and put under thorough control practically every physicist in the country having background knowledge of the subject, but the time for this has certainly not arrived." This is a remarkably broad concept — that "practically every physicist in the country" might need to be put under government control, but this is an important indicator both of Bush's views about the practical utility of secrecy (as a form of human control) and about the impending importance of the work, despite not yet being a bomb production program (this just predates the establishment of the Manhattan Project).
President Franklin Roosevelt to Vannevar Bush, authorizing the Manhattan Project, March 1942
Franklin D. Roosevelt to Vannevar Bush (11 March 1942), Bush-Conant File Relating the Development of the Atomic Bomb, 1940-1945, Records of the Office of Scientific Research and Development, Record Group 227, microfilm publication M1392, Washington, DC: National Archives and Records Administration, n.d. (ca. 1990), Roll 1, Target 3, Folder 2, "S-1 Historical File, Section B (1941-42)."
In this small note from President Roosevelt to Vannevar Bush, Roosevelt briefly extends the authorization for the creation of the Manhattan Project — the Army-led project to build actual nuclear weapons, not just research their feasibility — and couples with it for a requirement for “absolute secrecy.” The latter becomes interpreted over the years of the Manhattan Project’s tenure as a mandate for unprecedented levels of secrecy, including keeping secret the fact that there was a secret project in the first place. In the book, the origins of this mandate are explored, as well as the motivations of Roosevelt for requiring it for this above all other wartime secret projects. Also included in this file is the memo from Bush that Roosevelt was replying to.
Memo by J. Robert Oppenheimer, establishing information dissemination policy at Los Alamos, 1943
J. Robert Oppenheimer, "Dissemination of Information," (21 June 1943), Manhattan Engineer District (MED) records, Records of the Army Corps of Engineers, RG 77, National Archives and Records Administration, Box 65, "Publications."
The isolated Los Alamos laboratory was created out of a fear that universities — the primary sites of fission research prior to the establishment of the Manhattan Project — were overly porous and uncontrollable. However even within the new, secret laboratory, there were internal divisions of how information was disseminated, in line with General Groves' demand for totalizing "compartmentalization," or "need-to-know." This memo from Los Alamos director J. Robert Oppenheimer outlines the policies, and attempts to articulate a middle-ground between the total exchange preferred by most of the scientists, and Groves' stifling compartmentalization.
Account of "Nicholas Baker" (Niels Bohr) by Manhattan Project security, 1944
Manhattan Engineer District (MED) records, Records of the Army Corps of Engineers, RG 77, National Archives and Records Administration, College Park, Maryland, Box 64, "Security."
This memo from John Lansdale, Jr., the head of Manhattan Project intelligence and security, to Richard Tolman, a physicist advisor to General Leslie Groves, tells of the daring actions taken by a protective surveillance team to save the scientist with the code-name "Nicholas Baker" — the famed quantum physicist Niels Bohr — and his son Aage from themselves. "Both father and son appear to be extremely absent-minded individuals, engrossed in themselves, and go about paying little attention to external influences," Lansdale quotes the observing agent. Only "resourceful work" by one of the agents prevented them getting hit by a car as they wandered through an automobile intersection, heedless of traffic. Amusement value aside, the document also reveals the way in which Manhattan Project security operated: always watching, even if unperceived by those being watched.
Memorandum on international control by Niels Bohr, 1944
Memorandum by Niels Bohr (3 July 1944), in Correspondence ("Top Secret") of the Manhattan Engineer District, 1942-1946, microfilm publication M1109 (Washington, D.C.: National Archives and Records Administration, 1980), Roll 3, Target 5, Folder 20, "Miscellaneous."
After being smuggled out of Nazi-occupied Denmark, Niels Bohr eventually made his way to the United States, where he was shown the great endeavor of the Manhattan Project that was well under way, and he marveled at it, as he does in this Top-Secret classified essay: "What until a few years ago might have been considered a fantastic dream is at the moment being realized in great laboratories erected for secrecy in some of the most solitary regions of the States." Bohr, sooner than most, became preoccupied with the question of what would happen after such a weapon was created, and how it would affect the possibility of world affairs — or world extinction. In this memo from July 1944, Bohr attempts to systematically tackle the situation, concluding, in the end, that the idea of continued secrecy was a fallacy, and that the problem demanded an "openness" in exchange. Only a world of free interchange of information, Bohr would later elaborate, could avoid a deadly nuclear arms race. Though Bohr was able to get audiences with both Roosevelt and Churchill, he was unable to persuade them of the merit of his arguments, but he had more luck with other scientists at Los Alamos, notably J. Robert Oppenheimer.
Letter from Rep. Albert Engel to Henry Stimson, February 1945
Albert Engel to Henry L. Stimson (23 February 1945), in Harrison-Bundy Files Relating to the Development of the Atomic Bomb, 1942-1946, microfilm publication M1108 (Washington, D.C.: National Archives and Records Administration, 1980), Roll 1, Target 2, Folder 2, "Appropriations."
The Manhattan Project was not just secret from the Germans and the Japanese, it was a secret from the American people as well. This included the US Congress, who were feared by the project leaders: German knowledge of the American atomic bomb project probably couldn't stop it, but Congressional knowledge could, if the Congressmen cut the funding or forced a public debate on it. Over the course of the war, several Congressmen (including, famously, Senator Harry Truman) attempted to audit the project, having gotten wind of some of the major production sites, and being aware of the increasingly large budget allocations assigned to the mysterious "Manhattan" category. This particular document comes from Representative Albert Engel (R-MI), and is letter to the Secretary of War, Henry Stimson, explaining his frustration with being denied information about the project, and his incredulity at some of the rumors: "My information is that Dr. Conant of Harvard and other scientists sold the idea to the President and that it involved the job of 'breaking down the atom.' I was informed that 'a barrel of it would destroy Berlin and keep it burning for a year' and other similar statements equally fantastic." He threatened that, were he not let in on the secret, he would strike down their budget and air publicly his concerns and the rumors he had heard. Stimson did not waver in keeping him out of the loop, and Engel eventually got into line.
Leslie Groves to Harvey H. Bundy, "Visit of Seven Indian Scientists to the United States," (22 March 1945), in Harrison-Bundy Files Relating to the Development of the Atomic Bomb, 1942-1946, microfilm publication M1108 (Washington, D.C.: National Archives and Records Administration, 1980), Folder 62: "Security (Manhattan Project)," Roll 4, Target 8. Wallace Murray to James C. Dunn, Correspondence ("Top Secret") of the Manhattan Engineer District, 1942-1946, microfilm publication M1109 (Washington, D.C.: National Archives and Records Administration, 1980), Folder 12: "Intelligence and Security," Roll 2, Target 6.
In January 1945, a group of seven prominent Indian scientists visited the United States, as part of a cultural exchange delegation chartered by the Royal Society. While visiting, they apparently got wind of the fact that the United States was in the business of manufacturing nuclear bombs, and asked about touring the uranium enrichment facility in Tennessee. This set off alarm bells in the Manhattan Project security system, who wanted to figure out exactly where — if anywhere — a leak had occurred. The Indians were not pleased by the treatment, and claimed that they had simply deduced it, as any technical person might have been able to. This fascinating episode has not be written about outside of my book. These two memos, one from General Groves to the Secretary of War's assistant, Harvey Bundy, and another describing the Indian scientists and their visit transmitted to the Assistant Secretary of State, summarize the event and the American reaction to it.
Letter from Edward Teller to Leo Szilard, July 1945
Edward Teller to Leo Szilard, (2 July 1945), Papers of J. Robert Oppenheimer (MSS35188), Library of Congress, Box 71, Folder, "Teller, Edward, 1942-1963."
In the summer of 1945, two Hungarian scientists who were members of the Manhattan Project — Leo Szilard and Edward Teller — had an interesting interaction. Szilard had encouraged Teller, and others, to join in a petition he was circulating within the project against the use of the bomb. Teller responded back with the following letter, which he also copied to J. Robert Oppenheimer. In it, Teller explains why he doesn't feel that it is his place to object to how the military uses the weapon he had helped create. For him, the important thing was "in getting the facts of our results before the people," as that "might convince everybody that the next war would be fatal." For this, he admitted, "actual combat use might even be the best thing." But he identifies his real enemy, in the end, as secrecy: "This is the only cause for which I can feel entitled in doing something: the necessity of lifting the secrecy at least as far as the broad issues of our work are concerned." Teller would later go on to regret the bombing of Hiroshima, but he continued in his anti-secrecy attitude through his long career as a government weapons scientist.
Notes on a meeting about the Smyth Report, August 1945
W.H. Kyle, "Notes of a Meeting on the Smyth Report in the Office of the Secretary of War" (2 August 1945), in Correspondence ("Top Secret") of the Manhattan Engineer District, 1942-1946, microfilm publication M1109 (Washington, D.C.: National Archives and Records Administration, 1980), Folder 12: "Intelligence and Security," Roll 2, Target 6.
Only a few days before the Hiroshima attack, a major policy issue still remained: should the United States release the Smyth Report, a technical and administrative history of the Manhattan Project, immediately after the weapon was dropped? The historical project had been begun the year before, but its final disposition was not settled. As the notes of the meeting record, there were strong and sharp arguments on both sides of it, from people like General Groves, Secretary of War Stimson, and Harvard President James Conant, and strong resistance from members of the British delegation to the Manhattan Project, whose assent was required by the Quebec Agreement of 1943. What would be gained, and what would be lost, with such a disclosure? Ultimately, the decision would lie with Truman, and not be resolved until after both atomic bombings had taken place.
Report of the Committee on Declassification, November 1945
Report of the Committee on Declassification (11 November 1945), Manhattan Engineer District (MED) records, Records of the Army Corps of Engineers, RG 77, National Archives and Records Administration, Box 49, "Committee on Declassification." The first and last pages are from this original copy (Groves' own); the interior pages are a scan of copy #3 made by the Department of Energy.
In the fall of 1945, after it became clear that postwar atomic energy legislation was going to be delayed, General Groves requested that J. Robert Oppenheimer come up with an interim system for determining what should or should not be released about wartime nuclear research. This eventually resulted in the creation of a committee chaired by physicist Richard Tolman, and featuring the talents of top-scientists Robert Bacher, Arthur Compton, Ernest Lawrence, J. Robert Oppenheimer, Frank Spedding, and Harold Urey, which dubbed themselves the Committee on Declassification. After deliberation for several days in Tolman's office in Pasadena, they authored a report in November 1945 which became the foundation for all future nuclear declassification policy, articulating a system that was based around document declassification (not concept declassification), and a unique taxonomy of knowledge that, unlike the previous wartime secrecy regime, recognized that "danger" came in shades of gray rather than pure black and white.