Donald Trump, in the wake of last week’s deadly attack on Dallas police and a fresh wave of protests over police-involved shootings, voiced his full-throated support Monday for America’s law enforcement and declared himself the “law and order candidate.” The presumptive Republican presidential nominee put himself foursquare behind police at a combustible time in the relationship between law enforcement and the communities they serve. Speaking at an address in Virginia Beach originally billed as a veterans policy speech, Trump opened by discussing the deep challenges police face. “We will always stand with you,” Trump said. He compared the atmosphere to...