1. Attorney General Jeff Sessions announced a new push to investigate and prosecute leaks, in the wake of a slew of unauthorized disclosures that have plagued the Trump administration.

He vowed that the Justice Department would bring criminal charges against leakers of classified information, and said that the F.B.I. had created a new unit to manage the cases. The move comes 10 days after President Trump tweeted that Mr. Sessions had been “very” weak on pursuing such investigations.