KYIV, Ukraine (AP) — Officials say Ukraine could face rolling blackouts through March because Russian airstrikes have caused what they call “colossal” damage to the power grid. To cope in the harsh winter, authorities are urging Ukrainians to stock up on supplies and evacuate hard-hit areas. Russia has been pummeling Ukraine’s power grid and other infrastructure for weeks. That onslaught has caused widespread blackouts and deprived millions of Ukrainians of electricity, heat and water. The head of Ukraine’s power grid operator says the attacks have damaged practically every thermal and hydroelectric power plant. In another development, the United States announced $4.5 billion in aid to bolster Ukraine’s economic stability and support core government services.