Sentence:  Operation Highjump has turned out to be a hot topic for UFO conspiracy theorists over recent years, who claim it was a secret US military campaign to defeat and destroy supposed secret Nazi facilities in Antarctica and seize the German <WSD>Vril</WSD> flying discs, and the Thule mercury propelled spacecraft. 
Meaning of the word marked with <WSD> tags:  A kind of flying saucer supposedly built by the Nazis.