The United States has imposed sanctions on all of Iran's remaining active airlines, sharply escalating pressure on Tehran's aviation sector as part of a broader campaign aimed at cutting the Islamic Republic off from international trade and finance. The US Treasury Department on September 8 sanctioned 36 targets, including 27 Iranian airlines, as well as foreign companies and an individual accused of helping Iran's sanctioned aviation networks procure aircraft, aircraft parts, and other technology. The action marks the first time Washington has…