Former US vice president Joe Biden attacked President Donald Trump on Saturday over a report that he said, contains a truly shocking revelation about the commander in chief and his failure to protect US troops in Afghanistan and stand up to Russia. American intelligence officials concluded months ago that a Russian military intelligence unit secretly offered bounties to Taliban-linked militants for killing US troops in Afghanistan. Russians offered rewards for successful attacks last year, at a time when the US and Taliban were holding talks to end the long-running war. Biden, the presumptive Democratic nominee, described the revelations as horrifying.