US defence secretary Mark Esper breaks with Donald Trump on sending the army to clamp down on protests, and his predecessor James Mattis joins the president’s critics. The  FT’s Katrina Manson explains why the rift is so significant. Plus, a study casts doubt on whether taking hydroxychloroquine is an effective treatment for Covid-19, and Warner Music scored the biggest US IPO of 2020 on Wednesday. See acast.com/privacy for privacy and opt-out information.