In 1967, Egypt blocked the Gulf of Aqaba to Israeli shipping. On May 17, Egyptian leader Gamal Abdel Nasser demanded that UN monitoring forces evacuate the Sinai, a request with which UN Secretary-General U Thant cowardly complied. Nasser began the re-militarization of the Sinai, and concentrated tanks and troops on the border with Israel. On May 22, Egypt closed the Straits of Tiran to Israeli shipping, and blockaded the Israeli port of Eilat in the Gulf of Aqaba. The Egyptian blockade violated international law and Israel demanded that it cease. When Egypt failed to act, Israel launched a pre-emptive attack that destroyed 300 airplanes -- nearly the entire Egyptian Air Force -- in a matter of hours. Within days Israel had captured the entire Sinai Peninsula; this would be the bargaining chip for the Israeli-Egyptian Peace Accords of 1979.