Attorneys general from 18 states sued President Trump on Tuesday to block an executive order that refuses to recognize the U.S.-born children of unauthorized immigrants as citizens, the opening salvo in what promises to be a long legal battle over the Trump administration’s immigration policies.D.C.The complaint, filed in Federal District Court in Massachusetts was joined by the cities of San Francisco and Washington, D.C.The states view Mr. Trump’s attempt to limit birthright citizenship as “extraordinary and extreme,” said New Jersey Attorney General Matthew J. Platkin, who led the legal effort along with the attorneys general from California and Massachusetts. “Presidents...