"It's a classic," Boghardt, the International Spy Museum's historian, says of this 4.5 millimeter single-shot weapon, presumably taken from a KGB agent in the mid-1960s. While it's unclear whether this dangerous "kiss of death" was ever used, a cyanide pistol was used for assassination in that era. These covert weapons are surviving examples of the "active measures" that were taken in this time period, unlike many of their intended targets.