KYIV, Ukraine — Ukraine is working to resume prisoner exchanges with Russia that could bring home 1,200 Ukrainian prisoners, President Volodymyr Zelenskyy said Sunday, a day after his national security chief announced progress in negotiations. “We are ... counting on the resumption of POW exchanges,” Zelenskyy wrote on X. “Many meetings, negotiations and calls are currently taking place to ensure this.” Rustem Umerov, Secretary of Ukraine’s National Security and Defense Council, said Saturday