By Gabe Friedman A 96-year-old non-Jewish Holocaust survivor who lived through four different Nazi concentration camps was killed Friday in a Russian airstrike on the Ukrainian city of Kharkiv. The Buchenwald and Mittelbau-Dora Memorials Foundation announced Borys Romanchenko’s death on Twitter on Monday. “Survived Hitler, murdered by Putin,” Ukraine’s foreign minister tweeted Monday . Romanchenko’s former concentration camp uniform, which he wore through stints at the Buchenwald, Peenemünde, Dora and Bergen-Belsen camps, featured a red triangle . That symbolized that he was likely either a political prisoner or a gentile who assisted Jews, among other non-Jewish categories. Romanchenko was at...