The upheaval in the Pentagon in President Donald Trump’s final weeks in office began with the firing of Defense Secretary Mark Esper on Twitter, but it didn’t end there.

In the hours after, the Under Secretary of Defense for policy James Anderson, Under Secretary for Intelligence Joseph Kernan, and Esper’s Chief of Staff Jen Stewart all resigned. 

Mr. Anderson’s release was sudden, he resigned before he could be fired but Mr. Kernan’s had been planned.

Kash Patel, a controversial former aide to Republican Representative Devin Nunes, is replacing Ms. Stewart.