US President Joe Biden on Wednesday said he was not surprised by reports that Russian mercenary chief Yevgeny Prigozhin had died in a plane crash, adding that not much happens in the country that President Vladimir Putin is not behind. Analysts said the incident could be a way for Putin to warn others who might betray him or to show his support to the Russian military, whom Prigozhin undermined with an abortive armed mutiny in June.