National Academy of Sciences (NAS) recommended new radiation exposure limits for the general public in a report entitled: "The Biological Effects of Atomic Radiation". The AEC, which was the body that developed nuclear weapons, accepted the NAS recommended radiation exposure limits. Some AEC members asserted that the limits were reached incorrectly and should be reviewed in the future. Charles L. Dunham, AEC Director of the Division of Biology and Medicine (DBM), said that the new limits of nuclear radiation exposure would prevent them from continuing testing in Nevada. Dunham, in association with other AEC offices and officials, made recommendations to move further tests to the Pacific to eliminate the need to determine radiological fallout safety. Also in 1956, the AEC was designing a test series that included nuclear detonations which would release significant amounts of nuclear fallout. The series came to be known as Operation Plumbbob and took place in 1957 from April 24 to October 7. Operation Plumbbob was followed by Project 58/58A and Operation Hardtack I. At the time of testing, Operation Plumbbob was the most extensive nuclear test series held at the Nevada Test Site. President Eisenhower was very cautious in approving Plumbbob due to public concern. Consequently, the AEC held brief and ultimately fruitless discussions of moving some of the tests in the Plumbbob series to the next planned Pacific Ocean series, Operation Hardtack I, to minimize radioactive fallout in and around the Nevada Test Site. When Operation Plumbbob began in the spring of 1957, the planning process of Operation Hardtack I was well underway and the number of nuclear detonations planned were more than those in the Plumbbob series. At the same time, radiation and nuclear proliferation concerns around the world had led to formal discussions between the US, USSR, and other countries on the topic of instituting a global ban on nuclear testing as a path to disarmament. In 1957 on August 9 AEC chairman Lewis L. Strauss proposed to President Eisenhower a preliminary plan of Operation Hardtack I. President Eisenhower objected to the length of the four-month testing period and that the plan called for 25 shots, which was one more than in Plumbbob. As a result of the discussion, Eisenhower consented to yields no larger than , and ordered that the testing period be as brief as possible. Project 58/58A followed Operation Plumbbob and began almost two months later starting in 1957