Operation: Purloin was the codename of a Starfleet Intelligence mission to infiltrate Romulan space and capture a cloaking device.

Starfleet Intelligence began making preparations for the mission in 2267 and assigned the mission to Captain James T. Kirk of the USS Enterprise in 2268. (FASA RPG module: Star Trek IV Sourcebook Update) Despite the Enterprise being captured by Romulan forces, Kirk successfully stole the cloaking device of Commander Charvanek's vessel and captured the commander herself, with the help of his first officer Commander Spock, before escaping Romulan space. (TOS episode: "The Enterprise Incident")

The cloaking device was publicly tested aboard a Federation ship later that year with a number of dignitaries aboard. The ship and its accompanying observation vessel disappeared. An explosion quickly followed and neither ship was seen again. (FASA RPG module: Star Trek IV Sourcebook Update)