Last month, Ukraine quietly asked the United States and NATO for sensitive equipment to jam the radars that Russian anti-aircraft systems use to lock their missiles on planes. As the United States and NATO last month began to publicly acknowledge the sophisticated Russian anti-aircraft systems moving into rebel held areas of eastern Ukraine, the government in Kiev asked for gear that might be used to counter those weapons. According to a former senior U.S. defense official who has worked closely with Ukraine’s military and a former head of state who has consulted with the government there, Kiev last month requested...