Donald Trump’s attempt to bully his Nato allies into handing over Greenland by imposing tariffs is, even by his standards, a step too far. The President is used to getting what he wants — to use his own words, “the soft way or the hard way”. And with one eye on his historical legacy, Mr Trump seems determined to purchase or annex the Arctic island, even if in the process he unleashes a trade war and destroys the Atlantic alliance. Nothing can justify this exercise of raw power. The US already has a base in Greenland and could, if it...