Trump Ousts DHS Chief as Border Promises Unravel Ahead of 2020

Donald Trump’s frustration over his inability to fulfill his signature 2016 campaign promise to curb illegal immigration led him to oust his second homeland security chief, as the president eyes his re-election prospects next year.

Homeland Security Secretary Kirstjen Nielsen resigned at Trump’s request after a meeting with him on Sunday at the White House residence, according to people familiar with the matter. Her departure follows Trump’s decision last month to give a larger say on immigration policy to a hard-line aide, Stephen Miller, who had complained that Nielsen was...