As calculations by Ulam, Everett and Fermi made it increasingly clear that Teller's design for the thermonuclear bomb (the so-called 'classical super') would not work, Teller became bitterly critical of Los Alamos, and campaigned for his own lab.
In fact the failure was Teller’s, Hans Bethe observes, not the laboratory’s: That Ulam’s calculations had to be done at all was proof that the H-bomb project was not ready for a “crash” program when Teller first advocated such a program in the fall of 1949. Nobody will blame Teller because the calculations of 1946 were wrong, especially because adequate computing machines were not then available. But he was blamed at Los Alamos for leading the Laboratory, and indeed the whole country, into an adventurous program on the basis of calculations which he himself must have known to have been very incomplete.2138
Rhodes, Richard. Dark Sun: The Making Of The Hydrogen Bomb (p. 461). Simon & Schuster. Kindle Edition.