[5] The IRIAF had received "credible" reports that Iraq – reinforced by the arrival of large amounts of ammunition and spare parts from Egypt, as well as by the delivery of Mirage F1s from France and Tupolev Tu-22 bombers from the Soviet Union[6] – had been preparing for an imminent major ground and air offensive against Iran.[7] As part of Saddam Hussein's attempts to carry out a successful offensive against Iran on the northern front between 12 and 22 March 1981, Iraq fired two 9K52 Luna-M surface-to-surface rockets against the cities of Dezful and Ahvaz.[6] A team of IRIAF commanders (including Col. Ghasem Golchin, Col. Bahram Hooshyar and Col. Fereydoun Izadseta) planned a more sophisticated, surprise operation instead.To increase their chances, the Iranian commanders decided to fly their aircraft to Urmia Lake first, refuel in the air, and then from there have a "clean" route passing over the mountains of northern Iraqi–Turkish border, while keeping the altitude at less than 300 ft (100 m) to avoid Iraqi and Turkish radars.Some time earlier, the two tankers, which already had been sent to Syria, had taken off from a Syrian airport, and then clandestinely diverted from international commercial corridors in total radio silence, while apparently being bound for Iran.Flying at a very low altitude over southern Turkey and eastern Syria, they crossed mountainous northwestern Iraq and finally joined the Phantoms over the western Iraqi desert.Iraq claimed that the bombers were stationed at Tammuz until they were retired from the Iraqi Air Force in the late 1980s, and then were bombed in 1991 during the Gulf War.[14] Iraqi air defense command later claimed to have detected the formation coming from the direction of Syria en route to the target, and their radar followed Phantoms for some 67 minutes,[15] although the Iranians achieved total surprise.