The US Justice Department has threatened local and state authorities with prosecution if they fail to cooperate with President Donald Trump's immigration policies, which include a pledge to deport millions of undocumented immigrants.

President Trump’s pardons in the Jan. 6 case abruptly ended the most complex investigation in U.S. history. It also raised questions about what he will do next against a department he has said is full of his enemies.

The Trump administration is directing the Justice Department to dramatically boost its efforts on immigration enforcement, making it an agency top priority.

The Department of Justice is already experiencing sweeping changes under the Trump administration. The president has issued an executive order taking aim at what he calls the "weaponization" of the Justice Department.