UPDATE: US shutdown begins as no deal between lawmakers and Trump

A move Defense Secretary James Mattis is calling a betrayal of their alliance. Mattis has since submitted his letter of resignation. Courtesy #DStv403

WASHINGTON - The US government began a Christmastime shutdown early Saturday, after Congress adjourned without passing a federal spending bill or addressing President Donald Trump's demand for money to build a border wall.

Operations for several key agencies ceased at 12:01am Saturday (5:01 GMT), despite last-ditch talks that continued on Capitol Hill between White House officials and congressional leaders in both parties.