Operation Gladio is the codename for a clandestine North Atlantic Treaty Organisation (NATO) "stay-behind" operation in Italy during the Cold War. Its purpose was to prepare for, and implement, armed resistance in the event of a Warsaw Pact invasion and conquest. Although Gladio specifically refers to the Italian branch of the NATO stay-behind organizations, "Operation Gladio" is used as an informal name for all of them. The name Gladio is the Italian form of gladius, a type of Roman shortsword. Stay-behind operations were prepared in many NATO member countries, and some neutral countries.