by Stafford L. Warren, the Manhattan Project's chief physician, concerning the detrimental health effects of atmospheric testing, agreeing instead with James Bryant Conant, a chemist and participant in the Manhattan Project, who was skeptical of Warren's then-theoretical claims. Warren's arguments were lent credence in the scientific community and public by the Castle Bravo test of 1954. Eisenhower, as president, first explicitly expressed interest in a comprehensive test ban that year, arguing before the National Security Council, "We could put [the Russians] on the spot if we accepted a moratorium ... Everybody seems to think that we're skunks, saber-rattlers and warmongers. We ought not miss any chance to make clear our peaceful objectives." Then-Secretary of State John Foster Dulles had responded skeptically to the limited arms-control suggestion of Nehru, whose proposal for a test ban was discarded by the National Security Council for being "not practical." Harold Stassen, Eisenhower's special assistant for disarmament, argued that the US should prioritize a test ban as a first step towards comprehensive arms control, conditional on the Soviet Union accepting on-site inspections, over full disarmament. Stassen's suggestion was dismissed by others in the administration over fears that the Soviet Union would be able to conduct secret tests. On the advice of Dulles, Atomic Energy Commission (AEC) chairman Lewis Strauss, and Secretary of Defense Charles Erwin Wilson, Eisenhower rejected the idea of considering a test ban outside general disarmament efforts. During the 1952 and 1956 presidential elections, Eisenhower fended off challenger Adlai Stevenson, who ran in large part on support for a test ban. The British governments of 1954–58 (under Conservatives Winston Churchill, Anthony Eden, and Harold Macmillan) also quietly resisted a test ban, despite the British public favoring a deal, until the US Congress approved expanded nuclear collaboration in 1958 and until after Britain had tested its first hydrogen bombs. In their view, testing was necessary if the UK nuclear program were to continue to develop. This opposition was tempered by concern that resistance to a test ban might lead the US and Soviet Union to pursue an agreement without Britain having any say in the matter. Members of the Soviet military–industrial complex also opposed a test ban, though some scientists, including Igor Kurchatov, were supportive of antinuclear efforts. France, which was in the midst of developing its own nuclear weapon, also firmly opposed a test ban in the late 1950s. The proliferation of thermonuclear