The Obama administration said Wednesday that it is in the early stages of studying claims that Gulf airlines have received market-distorting subsidies, a review involving uncharted territory for the U.S. government. No international trade rules or precedent by the United States exists for addressing airline subsidy claims, presenting a challenge for the administration as it determines how to proceed, a person familiar with the matter said. U.S. airlines contend that Gulf carriers can lower prices and offer more amenities on newer planes because of state subsidies.