Nuclear weapons are thought of as being large and heavy, but even going back to 1950s, weapons designers had created weapons that could be carried in a backpack. But just how small can one of these devices be made and still work? There are stories of lost briefcase nukes after the fall of the Soviet Union, so in this video, we look at how they are and, with the widespread use of cheap drones in warfare, how likely it is that a stolen miniature nuke could be used in an unstable world today.