The Office of Foreign Assets Control (OFAC), the US Treasury bureau that runs American sanctions programmes, designated 27 Iranian airlines and nine foreign facilitators on Tuesday 8 September under Executive Order 13902 1. It suspended General Licence J-1, which had permitted temporary sojourns by certain Iranian civil aircraft, and issued General Licence DD so that affected transactions could be wound down 2.
The distinction between those two instruments does the work. A general licence is standing permission that nobody has to apply for: a carrier operating under it simply operates. A specific licence must be requested case by case, reviewed, and granted. Suspending J-1 does not ban the underlying activity outright. It moves that activity from a category where permission is assumed into one where permission must be sought, and the practical effect falls on aircraft that were already in the air under the old rule.
The National Iranian American Council had asked Treasury on 31 August to restore an earlier set of Iran general licences, covering remittances, education, conferences, sports and academic exchange, and received no reversal . Rather than answer that appeal, OFAC widened the same instrument to aviation on the day the earlier wind-down expired.
Commercial aircraft need certified spare parts, and certification is controlled by a small number of manufacturers and regulators in jurisdictions that enforce US designations. An airline cut off from that chain does not stop flying immediately; it flies on cannibalised parts and deferred maintenance until an airworthiness authority or an insurer refuses to carry the risk. The constraint arrives quietly and then all at once.
