In the four years following the Suez Crisis, repeated U-2 missions over the Middle East were launched, particularly in times of tension. The end of the 1958 Lebanon crisis saw a decline in U-2 operations, although Detachment B U-2s operating from Turkey still sometimes overflew the Middle East along with occasional missions over Albania to check for Soviet missile activity. Israel was a major target of U-2 missions during this period, with U-2 missions detecting the construction of the Negev Nuclear Research Center in 1958, first bringing Israel's nuclear program to the attention of the US. The overflights drew the attention of the Israeli Air Force. Its radars detected and tracked the overflights, and on numerous occasions, Israeli fighter aircraft were scrambled to intercept them but were unable to reach them due to their altitude. The Israeli government was baffled by the overflights. However, Israeli fighter pilots were twice able to spot the intruding aircraft. On 11 March 1959, two Israeli Super Mystere fighters were directed to intercept a U-2 detected over Israel by Israeli ground-based radar. Although the aircraft were unable to make an intercept, the formation leader, Major Yosef Alon, managed to get a good look at the aircraft. He subsequently identified it out of a book as a U-2, registered as a weather reconnaissance aircraft to the US Weather Service. On 22 July 1959, after an overflight was detected, an Israeli Air Force Vautour jet was deployed to photograph the mysterious aircraft. The Vautour came within visual range and the U-2 was successfully photographed. In spite of this, it was not until the 1960 shootdown of a U-2 over the Soviet Union and its subsequent public exposure as a spy plane that the Israeli government understood the identity of the mystery aircraft.