LGM-30 Minuteman missile silos and, second, from developing a capable missile defense system. Third, it was argued that the Soviet Union led the US in high-yield weapons (recall the Soviet Tsar Bomba test of 1961), which required atmospheric testing banned by the treaty, while the US led the Soviet Union in low-yield weapons, which were tested underground and would be permitted by the treaty. Fourth, the ban would prevent peaceful, civilian uses of nuclear detonations. Teller declared that the treaty would be a "step away from safety and possibly ... toward war." Administration testimony sought to counteract these arguments. Defense Secretary Robert McNamara announced his "unequivocal support" for the treaty before the Foreign Relations Committee, arguing that US nuclear forces were secure and clearly superior to those of the Soviet Union, and that any major Soviet tests would be detected. Glenn T. Seaborg, the chairman of the AEC, also gave his support to the treaty in testimony, as did Harold Brown, the Department of Defense's lead scientist, and Norris Bradbury, the longtime director of the Los Alamos Laboratory. Maxwell D. Taylor, the Chairman of the Joint Chiefs of Staff, also testified in favor of the deal. Taylor and other members of the JCS, including Curtis LeMay, had made their support for the treaty conditional on four "safeguards": (1) a continued, aggressive underground testing program, (2) continued nuclear research programs, (3) continued readiness to resume atmospheric tests, and (4) improved verification equipment. Kennedy emphasized that the US would retain the ability to use nuclear weapons in war, would not be bound by the treaty if the Soviets violated it, and would continue an aggressive underground testing program. Kennedy also stressed that a ban would be a key step in preventing nuclear war. The testimonies of the Joint Chiefs were seen as particularly effective in allaying concerns, as were the reassurances issued by Kennedy, who had acquired a reputation for resoluteness against the Soviet Union in the wake of the Cuban Missile Crisis. Additionally, a number of prominent Republicans came out in support of the deal, including Eisenhower, Eisenhower's vice president Richard Nixon, and Senator Everett Dirksen, who had initially been skeptical of the treaty. Eisenhower's science advisor and former PSAC head, George Kistiakowsky, endorsed the treaty. Former President Harry S. Truman also lent his support. Supporters of the deal mounted a significant pressure campaign, with active lobbying in favor by a