By Marko Djurica and Abdelaziz Boumzar BUCHA, Ukraine (Reuters) – The United States and European countries pledged on Monday to punish Moscow over civilian killings in northern Ukraine, where a mass grave and tied bodies of people shot at close range were found in a town seized back from Russian forces. The deaths in Bucha, outside Kyiv, drew pledges of further sanctions against Moscow from the West, possibly including some restrictions on the billions of dollars in energy that Europe still imports from Russia. The discoveries came against a backdrop of artillery barrages in Ukraine’s south an…