The headline from Trump’s Davos speech is clear: I won’t use military force to take Greenland. That’s what the President told the world’s leading politicians and business executives at the World Economic Forum. That declaration was very good news for all of them and for US investors, who immediately started buying stocks, erasing about half the losses suffered Tuesday, when the threat of force seemed possible. They all knew that carrying out that military threat would shatter the institutional foundation of Western security: NATO and US-European relations. Instead of military threats, Trump emphasized America’s disproportionate contributions to European defense since...