Appointment of Army veteran and ex-lobbyist ends longest-ever Pentagon leadership vacuum in American history

Tehran denies its UAV was shot down in Strait of Hormuz by US naval ship after Trump announces clash

After a single day on the job, Mark Esper to meet with fellow NATO defense ministers as US seeks to enlist countries to counter threats to shipping in Persian Gulf

US president announces Mark Esper as nominee to lead the Pentagon; not clear whether industry background might complicate confirmation prospects

The US has no defense secretary and the temporary one just quit. His replacement might only stay for six weeks; top Democrat calls situation 'appalling'

Army Secretary Mark Esper will come in as acting Pentagon leader amid rising tensions in the Middle East

Foreign minister seems to suggest Tehran's enemies are behind assaults on ships in Persian Gulf, after Washington issues video it says shows Iranian forces interfering with vessel

Pentagon also sends out picture showing hole in side of Japanese vessel and alleged explosive device, as tensions escalate; Iran denies involvement

Acting US defense chief Shanahan considering steps after White House requested hiding ship named for dead Trump rival

As Pentagon mulls deploying more troops in Middle East, Iranian president says situation is 'more complicated' than the Iran-Iraq war of the 1980s