Trump wants to buy Greenland. Trump is making neo-imperialist noises about taking the Panama Canal away from Panama.
Look at a map. If the USA controls Greenland it controls who can use the NW Passage in both the East (Greenland) and in the West (Alaska). If the USA also regains control of the the Panama Canal then the USA would control how most shipping gets from the Atlantic Ocean to the Pacific Ocean and vise versa.
