Logo of the U.S. defense company Raytheon is pictured at an international military fair in Kielce, Poland September 7, 2017. REUTERS/Kacper Pempel

WASHINGTON (Reuters) - Raytheon Co RTN.N was awarded a $568 million defense contract for modifications to a Patriot missile defense system it is building as part of a foreign military sale to Sweden, the Pentagon said on Thursday.