US President Donald Trump has claimed ad nauseam that during World War 2, the US defended Greenland after Denmark fell to Nazi Germany and later returned the territory without asking for anything in return. But Trump never mentions one tiny but crucial piece of information. In return for defending Greenland, the US and its allies gained access to a highly valuable and exceedingly rare resource, cryolite. That mineral proved crucial for the US and its wartime allies in making fighter aeroplanes. advertisement Trump has repeatedly said he wants a deal with Greenland to tap its mineral resources and reduce China's...