There are also some indications that military experts within the Soviet Union saw a test ban as a way to restrict US development of tactical nuclear weapons, which could have increased US willingness to deploy small nuclear weapons on battlefields while circumventing the Soviet nuclear deterrent. Concern that a comprehensive ban would retard modernization of the Soviet arsenal may have pushed Khrushchev towards a partial ban. Counteracting the move towards a partial ban was Khrushchev's interest in reducing spending on testing, as underground testing was more expensive than the atmospheric tests the Soviet Union had been conducting; Khrushchev preferred a comprehensive ban as it would have eliminated the cost of testing entirely. Furthermore, there was internal concern about nuclear proliferation, particularly regarding the prospect of France and China crossing the threshold and the possibility of a multilateral NATO nuclear force, which was seen as a step towards West Germany acquiring nuclear weapons (the first Soviet test ban proposal in 1955 was made in the same month than West Germany joined NATO). It was not until after the agreement was reached that the negotiators broached the question of France and China joining the treaty. Harriman proposed to Khrushchev that the US lobby France while the Soviet Union pursued a Chinese signature. "That's your problem," Khrushchev said in reply. Earlier, the Soviet ambassador to the US, Mikhail A. Menshikov, reportedly asked whether the US could "deliver the French." Both Kennedy and Macmillan personally called on de Gaulle to join, offering assistance to the French nuclear program in return. Nevertheless, on 29 July 1963, France announced it would not join the treaty. It was followed by China two days later. On 5 August 1963, British Foreign Secretary Alec Douglas-Home, Soviet foreign minister Gromyko, and US Secretary of State Dean Rusk signed the final agreement. After the Moscow agreement Between 8 and 27 August 1963, the United States Senate Committee on Foreign Relations held hearings on the treaty. The Kennedy administration largely presented a united front in favor of the deal. Leaders of the once-opposed Joint Chiefs of Staff (JCS) and AEC acknowledged that the treaty would be of net benefit, though Teller, former members of the JCS and AEC, and the commander of the Strategic Air Command made clear their firm opposition. The opponents' argument centered on four themes. First, banning atmospheric tests would prevent the US from ensuring the hardness of its