Founded and ruled by a Varangian warrior elite and their descendants, the medieval state of Rus arose in the 9th century. Following the Russian Revolution, the Russian Soviet Federative Socialist Republic became the largest and leading constituent of the Soviet Union, the world's first constitutionally socialist state and a recognized superpower, which played a decisive role in the Allied victory in World War II. The country is one of the five recognized nuclear weapons states and possesses the largest stockpile of weapons of mass destruction.