This talk explores how the global history of the Cold War played out through two semi-secretive technological projects of the period. The first was the attempt, during the 1950s and 1960s, to overcome massive communications failures in the Canadian North – naturally-occurring radio blackouts that would mask incoming ICBMs and disrupt shortwave technologies. The talk traces how these failures helped define the “hostile natures” of the Cold War, as well as Canada’s cultural anxieties and geo-political vulnerabilities during the period. The talk’s second focus is the late 1960s, where it traces the “supergun” projects of Gerald Bull, the former McGill professor turned international arms dealer. Bull’s ambiguous inventions – gargantuan cannons initially designed to launch probes into space – straddled the line between scientific instruments and illicit weaponry. Conceived in Montreal, deployed in Barbados, redesigned and sold to South Africa, and eventually enlarged and destined for Saddam Hussein’s Project Babylon, they would ultimately lead to Bull’s assassination at the hands of government agents outside his Brussels apartment. Contrasting the two episodes, the talk illustrates the crucial historical and geographical connections between Canadian science and technology and the broader, global contours of the Cold War.