As a private citizen over the past year, Vindman watched the slow Russian buildup along Ukraines borders and, he said, became concerned about how Kyiv would support and sustain a long conflict. Vindman and his twin brother Yevgeny, also an Army officer, were born in Ukraine and immigrated to the U.S. as children.Since the invasion last year, the Biden administration has approved hundreds of Bradley fighting vehicles, Strykers, Humvees, mobile howitzer systems and now Abrams tanks for shipment to Ukraine. But those machines must be taken from Ukraine to Poland or other NATO countries for major repairs, costing Ukrainian forces...