The declassification of the program was a large topic of discussion between scientists at all of the laboratories involved with the project and at the Sherwood conferences. The reasoning for an initial high classification status was that if the research into controlled fusion were to be successful then it would be a significant advantage in regards to military aspects. In particular, fusion products high-energy neutrons which could be used to enrich uranium into plutonium for nuclear bomb production. If a small fusion machine was possible, this represented a significant proliferation risk.
However, as the difficultly in making a working fusion reactor became increasingly clear, fears of hidden reactors faded. Additionally, while some of the required industrial work could be conducted without access to the classified information, there were some instances where the classified information of the program was a necessity for those people working on projects such as the large-scale stellarator, the ultra-high vacuum, and the problem of energy storage. In these instances, there was a contract with the Commission that the information that was being used would only be shared with the personnel that was directly working on the project. It soon became apparent that industrial companies were expected to become highly invested in the area of fission and because of this it became clear that these companies should have full access to the research information obtained by Project Sherwood. In June 1956, permits for the research information from Project Sherwood became available through the Commission for companies that were qualified.
Between 1955 and 1958, information became more and more available to the public with its gradual declassification beginning with the sharing of information with the United Kingdom. Huge supporters of declassification of the program included the director of the Division of Research, Thomas Johnson, and a member of his staff, Amasa Bishop. Some of their reasoning for wanting declassification was that the secrecy of the project could negatively impact their ability to enlist and employ experienced personnel to the program. The also argued that it would change the way their conferences could be held. The scientists working on the project would be able to freely discuss their findings with others in the scientific community rather than only the scientists working on the same project.
In 1956, Soviet physicist Igor Kurchatov gave a talk in the UK where he revealed the entire Soviet fusion program and detailed the problems they were having. Now that the very group of people the classification was intended to keep in the dark were at roughly the same stage of development, there was no obvious reason to continue classification. While the UK had been among the first to classify their program in the aftermath of the Klaus Fuchs affair in 1950, in the summer of 1957 they appeared to have successfully created fusion in their new ZETA and were clamoring to tell the press of their advances. Their agreement to share information with the US required them to classify their work, and now they also began pressing the US to agree to declassification.
By May 1958, basic information about the various projects within Project Sherwood including the stellarator, magnetic mirrors, and molecular ion beams had been released to the public.