technical findings themselves were accompanied by a caveat about the panel's high degree of uncertainty given limited data. Around the same time, analysis conducted by the Livermore National Laboratory and RAND Corporation at Teller's instruction found that the seismic effect of an underground test could be artificially dampened (referred to as "decoupling") to the point that a 300-kiloton detonation would appear in seismic readings as a one-kiloton detonation. These findings were largely affirmed by pro-ban scientists, including Bethe. The third blow to the verification negotiations was provided by a panel chaired by Robert Bacher, which found that even on-site inspections would have serious difficulty determining whether an underground test had been conducted. In September 1959, Khrushchev visited the US While the test ban was not a focus on conversations, a positive meeting with Eisenhower at Camp David eventually led Tsarapkin to propose a technical working group in November 1959 that would consider the issues of on-site inspections and seismic decoupling in the "spirit of Camp David." Within the working group, Soviet delegates allowed for the timing of on-site inspections to be grounded in seismic data, but insisted on conditions that were seen as excessively strict. The Soviets also recognized the theory behind decoupling, but dismissed its practical applications. The working group closed in December with no progress and significant hostility. Eisenhower issued a statement blaming "the recent unwillingness of the politically guided Soviet experts to give serious scientific consideration to the effectiveness of seismic techniques for the detection of underground nuclear explosions." Eisenhower simultaneously declared that the US would not be held to its testing moratorium when it expired on 31 December 1959, though pledged to not test if Geneva talks progressed. The Soviet Union followed by reiterating its decision to not test as long as Western states did not test. In early 1960, Eisenhower indicated his support for a comprehensive test ban conditional on proper monitoring of underground tests. On 11 February 1960, Wadsworth announced a new US proposal by which only tests deemed verifiable by the Geneva System would be banned, including all atmospheric, underwater, and outer-space tests within detection range. Underground tests measuring more than 4.75 on the Richter scale would also be barred, subject to revision as research on detection continued. Adopting Macmillan's quota compromise, the US proposed each nuclear state be subject to roughly 20 on-site inspections per year (the precise figure based on the