Austria

Austria was a nation state which existed on Earth during the 20th century. A close neighbor to Germany, Austria allied herself to Germany both during World War I and World War II. Austria had previously been annexed by Germany in 1938, an event which was commemorated by a medal issued by the Nazi government under Adolf Hitler. (VOY: "The Crying Game"; ENT: "Occluded Front").
The composer Johannes Brahms was also a native of Austria. (TOS: Elegy for the 2,000 Year Old Man).
:While Austria has never been directly mentioned in any episode of Star Trek, the country's existence can be implied (or inferred, even), by the "Anschluss Medal" which can be seen on German uniforms in both "The Crying Game" and "Occluded Front".
:We're sure that Austria would be pleased to hear this.