President-elect Donald Trump has confirmed on his social media network that he plans to use the US military to carry out a mass deportation of undocumented migrants. On Monday, he posted "TRUE!!!" in response to a conservative commentator who wrote that Trump would declare a national emergency and use military assets to lead “a mass deportation program”.

As state, county and city law enforcement leaders evaluate their legal options to refuse assistance — or offer it — to federal agents, competing tactics could emerge. And immigration advocates warn different policies among government agencies will breed confusion.