Complex sentence: Internationally, U.S. Steel operates facilities in Slovakia (former East Slovakian Iron Works in Košice) and Serbia-former Sartid with facilities in Smederevo (steel plant, hot and cold mill) and Šabac (tin mill).
Split into simpler sentences: Internationally, U.S. Steel operates facilities in Slovakia (former East Slovakian Iron Works in Košice). It also operated facilities in Serbia-former Sartid with facilities in Smederevo (steel plant, hot and cold mill) and Šabac (tin mill).