This article focuses on the U.S. diplomat and nuclear arms control negotiator Gerald (Gerry) Coat Smith in order to cast new light on the importance of diplomats in the context of the set of international activities currently labelled as “science diplomacy.” Smith, a lawyer by training, was a key negotiator in many international agreements on post‐WW2 atomic energy projects, from those on uranium prospecting and mining, to reactors technologies to later ones on non‐proliferation and disarmament. His career in science (nuclear) (...) diplomacy also epitomized the shortcomings of efforts to align other countries’ posture on nuclear affairs to U.S. wishes. In particular, the unswerving diplomat increasingly understood that strong‐arm tactics to dissuade other countries from acquiring nuclear weapons would not limit proliferation. Not only did this inform later U.S. diplomacy approaches, but it lent itself to the ascendancy of the new notion of “soft power” as critical to the re‐definition of international affairs. (shrink)