SA-6 uses semi-active radar homing and was paired with the 1S91 "Straight Flush" fire control and guidance radar, which operates in the G, H, I and J bands, making it very difficult to jam with the AN/ALQ-87 ECM pods that were supplied by the Americans prior to the conflict. Likewise, the AN/ALR-36 radar warning receivers that Israeli Phantoms were equipped with at the time proved unable to provide any warning to aircrews that their aircraft were being tracked by SA-6 battery crews using the Straight Flush radar. Some aerial maneuvers were believed to fool the SA-6 systems and these were used while the IDF waited for better ECM weapons. Some of the maneuvers were quite effective, but the SA-6 threat was only reduced on 9 October 1973 when A-4s surprised many SA-6 batteries without their missiles ready to fire and destroyed them. That same day another F-4 strike hit the Damascus HQ of the Syrian Army. By the middle of October, 37 Phantoms had been lost in combat and another six were damaged beyond repair. U.S. President Richard Nixon authorized the delivery of 36 ex-USAF F-4s under Operation Nickel Grass, from the USAF 4th and 401st Tactical Fighter Wings. These aircraft were flown directly to Israel, some by U.S. pilots. At least one F-4E flew in combat still bearing a U.S. tail code, while others stayed painted in USAF camouflage patterns. During the war Israeli Phantoms first used the new AGM-65 Maverick missile. Israel employed three F-4E(S), which were equipped with a special high-altitude camera system (HIAC) for reconnaissance missions. These RF-4Es were special high-performance Phantoms, with the same cameras planned for the Mach 3.2 RF-4X that was cancelled in 1975. The camera performed well but mounting it in an external pod caused too much drag, so it was installed in the nose of three normal F-4Es instead. During the Yom Kippur War it was reported that one Israeli F-4 Squadron was put on alert for a nuclear strike, but not confirmed. After several weeks of combat, losses included four F-4s delivered under the Nickel Grass program. Post 1973 period After the war Peace Echo V provided Israel with 24 new, 24 ex-USAF and 6 RF-4Es, completing the program in November 1976. Given that almost all the Israeli F-4s had suffered battle damage, an update to increase their capabilities and standardize the various production blocks was commenced in 1974. The