The mayor’s office in a key eastern Ukrainian city controlled by pro-Kremlin separatists was struck by rockets, Russian state agencies reported. According to the separatist authorities, four people were injured. According to RIA Novosti, the municipal building in Donetsk was “seriously damaged” by the attack, which local separatist authorities blamed on Ukraine. Kremlin-backed separatist authorities have previously accused Ukraine of numerous strikes on infrastructure and residential targets in the occupied territories, often employing the U.S.-supplied long-range HIMARS rockets, without provi…