Alexei Navalny, Russia’s opposition leader and Vladimir Putin’s staunchest political adversary, said in an Instagram post on Tuesday that he is facing new criminal accusations which could extend his current prison sentence by 15 years if he is convicted. In March, Navalny was sentenced to nine years in prison for fraud and contempt of court, charges he claims are politically motivated. According to Navalny’s Instagram post, an investigator paid him a visit in jail and told him that authorities are now investigating him on charges of “creating an extremist group to fan hatred against officials and oligarchs” and attempting to organize unsanctioned rallies. The Kremlin has been targeting Navalny’s supporters, other opposition leaders, and independent journalists over the past year in what appears to be an effort to silence dissent.