Congress is investigating a billing dispute of at least $750 million between the Dutch firm Supreme Foodservice GmbH, the main supplier of food to U.S. troops in Afghanistan, and the Pentagon, reports CNBC. The dispute is over whether the rates charged by Supreme were proper based on the conditions in the war ravaged country and critical in light of an even larger follow-on contract estimated at between $10 billion and $30 billion over the next five years, although U.S. combat troops are expected to leave Afghanistan by the end of 2014.