The contribution of Hans Albrecht Bethe in enhancing the security by designing nuclear bombs and to guard against the hazards of such bombs is discussed. Hans used mix of new and old scientific knowledge, technical invention, educated guesswork, and brute-force computation for developing a bomb. He also arranged explosive lenses that transform multiple expanding detonation to compress the plutonium core. Hans and Gottfried explored a suite of countermeasure concepts against the various high-tech intercept techniques.