Western intelligence sources said two F-15I fighter-jets entered Syria near the Turkish border on Sept. 6. They said the U.S.-origin warplanes contained special equipment meant to track the surface-to-air network of the Syrian Air Force. The warplanes sought to test the capabilities of the new Russian-origin Pantsyr-S1E air defense systems that arrived in Syria in mid-August.

The Pantsyr radars detected the intrusion of the Israeli fighter-jets.

But the F-15s managed to interfere with the response of the SAM system, which could not track the Israeli aircraft. The SAMs fired, but didn't even come close to shooting down the Israeli aircraft.

The United States coordinated with Israel in the operation. The Pantsyr-S1E system has also been relayed to Iran and was expected to help protect strategic facilities, including nuclear sites.

The entire operation took place minutes. The Israel Air Force did not want to attack the short-range mobile Pantsyr and was not assigned on a reconnaissance missions. There was only one purpose to the operation: to determine the capability of the Pantsyr, a system that would be supplied to the United Arab Emirates later this year.