Austria's status of permanent neutrality was formalised through which 1955 international agreement?

The correct answer is the Austrian State Treaty, signed on 15 May 1955 in Vienna by the Allied occupying powers, the United States, the Soviet Union, the United Kingdom and France, together with Austria, formally ending the decade-long joint occupation that followed the Second World War. The treaty restored Austria's full sovereignty and independence, and shortly afterward, on 26 October 1955, the Austrian parliament passed a constitutional law declaring permanent neutrality, committing the country never to join military alliances or allow foreign military bases on its soil, a status that shaped Austria's Cold War-era identity as a bridge between East and West. The Treaty of Saint-Germain-en-Laye, offered as a distractor, was signed in 1919 after the First World War and dealt with the dissolution of the Austro-Hungarian Empire, recognising the independence of successor states and restricting Austria's union with Germany, an entirely different historical moment nearly four decades earlier. The Congress of Vienna, held in 1814 to 1815, reorganised the political map of Europe after the Napoleonic Wars and had nothing to do with twentieth-century occupation politics, though it is often confused with treaties bearing Vienna's name. The Treaty of Versailles, signed in 1919, primarily addressed Germany's post-war settlement, not Austria's, making it a frequently misapplied distractor in questions about Austrian history. A common exam confusion involves mixing up the multiple Vienna-associated agreements, the Congress of Vienna, the Vienna settlement and the Austrian State Treaty, simply because they share a city name across very different centuries. The essential revision point is to anchor the Austrian State Treaty firmly to 1955, Allied withdrawal, and permanent neutrality, distinguishing it clearly from the 1919 Saint-Germain and Versailles treaties and the 1815 Congress of Vienna.