During his tenure at Harvard, Watson participated in a protest against the Vietnam War, leading a group of 12 biologists and biochemists calling for "the immediate withdrawal of U.S. forces from Vietnam." In 1975, on the thirtieth anniversary of the bombing of Hiroshima, Watson was one of over 2000 scientists and engineers who spoke out against nuclear proliferation to President Gerald Ford, arguing that there was no proven method for the safe disposal of radioactive waste, and that nuclear plants were a security threat due to the possibility of terrorist theft of plutonium.