Last night’s Republican debate exposed a major divide between the candidates on the question of how best to deter illegal immigrants, with Donald Trump favoring razor wire and other candidates arguing for teams of hungry attack dogs or machine gun nests. Building on his argument that he represents a younger, forward-looking conservatism, Marco Rubio proposed using missile-equipped border patrol drones that could be piloted by anyone with an internet connection. “It looks and feels like a video game,” he said, “but you’re actually serving your country and defending the integrity of its borders.” Rubio pledged to have an iOS drone app launched within his first 100 days in office. “Not only is this a way to get more young people involved in civic life, it will allow us to close down most of the Department of Homeland Security, leading to cost savings that we can use for a bigger tax cut.”