US President Donald Trump lashed out on Friday at what he called a fresh threat against the country’s identity, taking aim at domestic “radicals and extremists” on the eve of America’s 250th birthday. In a speech dripping with patriotism, Trump lauded American exceptionalism and praised its past leaders, speaking at Mount Rushmore with its giant carved heads of four of his legendary predecessors. But he added at the foot of the iconic monument: “As we approach this magnificent anniversary, we...