Every new president makes a series of phone calls to leaders of other countries, especially our allies — to get to know each other, talk about what's going on in the world, that sort of thing. Like other presidents, Donald Trump has been making these calls, but they haven't always gone so well. Like a few days ago, when he called Mexican President Enrique Peña Nieto and, according to reports, threatened a military incursion across the Rio Grande.