KRAMATORSK, Ukraine (AP) — Ukrainian officials and international observers are raising concerns that Russia’s relentless attacks on the country’s eastern Donbas region carry echoes of an earlier devastating assault on the port of Mariupol. The fighting Friday focused on two key cities: Sievierodonetsk and nearby Lysychansk. Ukraine’s foreign minister warned that without a new injection of foreign weapons, Ukrainian forces would not be able to stop Russia’s advance in the region, where separatists claimed to have captured a railway hub. Now in ruins, the port of Mariupol was constantly barraged by Russian forces in a nearly three-month siege. The battle ended last week when Russia claimed its capture. More than 20,000 of its civilians are feared dead.