In 1975, Israel made a key compromise to withdraw from the strategic Giddi Pass and Mitla Pass in the Sinai Peninsula in exchange for monitoring by third parties. The United States established the Sinai Field Mission to monitor access to the passes utilizing seismic, aural and infra-red sensors monitored from three watch stations. The U.S. military also performed reconnaissance flights. U.S. monitoring was coordinated with the activities of UN peacekeepers. After an initial period of suspicion, the parties came to accept monitoring as routine. The system successfully distinguished between significant and inconsequential sensor activations. All violations were relatively minor and resolved by a Joint Commission. Political leaders in both countries eventually praised the system.