Teller's homeland of Hungary, where much of his family still lived, on August 20, 1949. Following the Soviet Union's first test detonation of an atomic bomb on August 29, 1949, President Harry Truman announced a crash development program for a hydrogen bomb. Teller returned to Los Alamos in 1950 to work on the project. He insisted on involving more theorists, but many of Teller's prominent colleagues, like Fermi and Oppenheimer, were sure that the project of the H-bomb was technically infeasible and politically undesirable. None of the available designs were yet workable. However Soviet scientists who had worked on their own hydrogen bomb have claimed that they developed it independently. In 1950, calculations by the Polish mathematician Stanislaw Ulam and his collaborator Cornelius Everett, along with confirmations by Fermi, had shown that not only was Teller's earlier estimate of the quantity of tritium needed for the H-bomb a low one, but that even with higher amounts of tritium, the energy loss in the fusion process would be too great to enable the fusion reaction to propagate. However, in 1951 Teller and Ulam made a breakthrough, and invented a new design, proposed in a classified March 1951 paper, On Heterocatalytic Detonations I: Hydrodynamic Lenses and Radiation Mirrors, for a practical megaton-range H-bomb. The exact contribution provided respectively from Ulam and Teller to what became known as the Teller–Ulam design is not definitively known in the public domain, and the exact contributions of each and how the final idea was arrived upon has been a point of dispute in both public and classified discussions since the early 1950s. In an interview with Scientific American from 1999, Teller told the reporter: The issue is controversial. Bethe considered Teller's contribution to the invention of the H-bomb a true innovation as early as 1952, and referred to his work as a "stroke of genius" in 1954. In both cases, however, Bethe emphasized Teller's role as a way of stressing that the development of the H-bomb could not have been hastened by additional support or funding, and Teller greatly disagreed with Bethe's assessment. Other scientists (antagonistic to Teller, such as J. Carson Mark) have claimed that Teller would have never gotten any closer without the assistance of Ulam and others. Ulam himself claimed that Teller only produced a "more generalized" version of Ulam's original design. The breakthrough—the details of which are still classified—was apparently the separation