Trump imposes new "hard-hitting" sanctions against Iran; Trump denies author's sexual assault accusation from 90s; Trump: U.S. does not seek military conflict with Iran; Sources: U.S. launched retaliatory cyber attack on Iran; Buttigieg confronts racial tensions ahead of first debate; Buttigieg admits lack of progress in solving long-standing racial issues in South Bend; Sanders would cancel all $1.6 trillion of student loan debt; Beto O'Rourke proposes "war tax" as part of veterans' plan; CNN Exclusive look at Warren campaign's policy-making machine; Axios: Vetting found red flags on many Trump admin members; Trump: Biggest mistake was making Sessions attorney general; RNC researcher to Axios: Vetting process for Trump was a disaster, s***-show; Trump's pick for border czar calls out DHS Secy: McAleenan is on "wrong side"; Pence refuses to answer if he thinks climate emergency is a threat via Knit