Global warming is making both places more important to global shipping and trade. To imagine the kind of future a hotter, dryer climate may bring, and the geopolitical challenges it will create, look no farther than two parts of the world that Donald Trump wants America to control: Greenland and the Panama Canal.

Former Trump national security advisor Robert O'Brien explained on FNC's "Sunday Morning Futures" why Donald Trump wants to buy Greenland and control the Panama Canal. Both Trump targets have given strong pushback regarding any potential takeovers,

Former Trump national security advisor Robert O'Brien told FNC's "Sunday Morning Futures" why Donald Trump is talking about buying Greenland and seizing back control of the Panama Canal. About the Panama Canal: "We love the Panamanians.

At first, he joked about Canada being an additional US state. Since, he has threatened to take back control of the Panama Canal. He also reiterated a desire from his first term to own the autonomous Danish territory of Greenland, which is not for sale.

In recent days the president-elect has called for asserting U.S. control over the Panama Canal and Greenland, showing that his “America First” philosophy has an expansionist dimension.

Trump again having designs on Greenland comes after the president-elect suggested over the weekend that the U.S. could retake control of the Panama Canal if something isn't done to ease rising shipping costs required for using the waterway linking the Atlantic and Pacific oceans.

Former national security adviser Robert O’Brien said in a Sunday interview that Denmark should let the U.S. “buy” Greenland if it cannot defend the self-governing country, noting the territory will become increasingly important in the coming years.

Denmark needs to do more than add dog sleds to defend Greenland, given its icy territory has it “on the front lines of the war against Russia and China,” ex-National Security Adviser Robert O’Brien said Sunday.