Russia widened its targets in Ukraine on Sunday with strikes on a military base just miles from the Polish border, as a top Ukrainian advisor said the capital Kyiv was itself now “a city under siege.” Meantime, the death toll in the strategic southern port city of Mariupol, facing acute deprivation amid a prolonged siege, has topped 2,000, officials there said. While western Ukraine has largely been spared so far, Russian air strikes overnight carried the war deep into the west, killing 35 people at a military base near Yavoriv, outside the city of Lviv — which is dangerously close to the fro…