Kevin Sweeney, Pentagon chief of staff, resigns

An informed source told CNN's Jake Tapper that the White House had forced Sweeney out. The source did not provide any additional information about the reason.

Sweeney, who retired as Rear Admiral in 2014, served under former Defense Secretary James Mattis, who announced his resigned December 20, in the wake of the plans of President Donald Trump to withdraw. the troops of Syria.

"Because you have the right to have a Defense Secretary whose points of view are better aligned with yours on these topics, among others, I think it's just that I leave my post, "wrote Mattis in his letter to the President.

Trump says he postponed Mattis' departure date to January 1, two months earlier than originally planned.

Mattis is the last senior executive to leave Trump's cabinet. Jeff Sessions was sacked Attorney General the day after the mid-term elections in November, Rex Tillerson was unceremoniously dismissed as Secretary of State in March and National Security Advisor, HR McMaster, was replaced .

Pentagon spokeswoman Dana White announced last month that she was leaving her post, a move that coincided with Mattis' resignation, intervened as part of an internal investigation by Department of Defense on his conduct.