Since cross-border operations started in July 2014, aid materials sent by UN organizations arrive at UN bases in Turkey, where materials are moved from Turkish international road transports (TIRs) to Syrian TIRs. Later, TIRs cross into Syria as aid convoys under the supervision of the UN. The aid is then distributed by the UN's local partners in Syria. The whole operation is coordinated by the United Nations Office for the Coordination of Humanitarian Assistance (OCHA).