According to Donald Trump, Pete Hegseth is doing a 'fantastic job' running the US military.  But this week one of his most senior officials, the Army Secretary, quit after months of tensions with Hegseth, who has already purged dozens of other senior generals and admirals.  Today, staff writer at The Atlantic Missy Ryan on the turmoil at the Pentagon, and how long Hegseth will continue to have Trump’s backing. Featured:  Missy Ryan, staff writer at The Atlantic