US Defence Secretary Pete Hegseth's sweeping shake-up of the Pentagon is causing turmoil within military leadership, most notably the resignation of Army Secretary Dan Driscoll, amid a broader push for cultural and structural reform. The upheaval comes as the US military is simultaneously stretched by Trump's confrontation with Iran over the Strait of Hormuz, raising concerns about whether the changes could weaken American military readiness and its network of global alliances at a critical moment.

Driscoll's departure followed repeated clashes with Hegseth over the pace and direction of army modernisation, particularly the integration of drone technology inspired by lessons from the Ukraine war. Driscoll reportedly accused Hegseth of blocking reform by removing generals responsible for it, prompting Republican Senator Thom Tillis to call for Hegseth's dismissal, and former National Security Adviser H.R. McMaster to voice alarm. Critics, including retired Navy captain Jon Duffy, say Hegseth has "hollowed out" senior military leadership, while Hegseth has publicly framed his tenure as ending "woke" policies, scrapping diversity programmes, banning beards, and sidelining top officers across the Army, Navy and Air Force.