President Obama on Thursday denounced Donald J. Trump's campaign promise to deploy a "deportation force" to round up millions of immigrants in the country illegally and send them home, calling it unrealistic and un-American. "The notion that we're going to deport 11, 12 million people from this country - first of all, I have no idea where Mr. Trump thinks the money's going to come from," Mr. Obama said in an interview with George Stephanopoulos of ABC News. "It would cost us hundreds of billions of dollars to execute that." "Imagine the images on the screen flashed around the world...