As I was watching YouTube videos of Ukrainian forces advancing against Russian troops, my mind flashed back to a conversation I had in a pizza restaurant in Kharkiv in July with a 50-year-old Ukrainian military volunteer whose moniker was Sergo. Despite a bad leg (seriously mangled during service in 2014, when Russia first invaded eastern Ukraine), Sergo left his construction business and rushed to the front when Russia threatened his city. “The people protected the government, not vice versa,” he told me. “All Kharkiv was furious at the invasion.” Together with a fellow veteran and tank speci…