Only on February 23, after an American tip-off,[6] did an Israeli Air Force (IAF) Sud-Ouest Vautour photograph the Suez Canal zone to bring back news that the 4th Armored Division had in fact left its garrison. A second flight over the Sinai a day later revealed the full extent of the Egyptian deployment. Egyptian forces had deployed both close to the border and in depth, and Israel's forces in the Negev, consisting of between 20 and 30 tanks, were now facing 500 Egyptian tanks and SU-100 tank destroyers.[1][7]