After the 1956 Suez Crisis, Egypt agreed to the stationing of a United Nations Emergency Force (UNEF) in the Sinai to ensure all parties would comply with the 1949 Armistice Agreements.[22] In the following years there were numerous minor border clashes between Israel and its Arab neighbors, particularly Syria. In early November, 1966, Syria signed a mutual defense agreement with Egypt.[23] Soon thereafter, in response to PLO guerilla activity,[24][25] including a mine attack that left three dead,[26] the Israeli Defence Force (IDF) attacked the village of as-Samu in the Jordanian-occupied West Bank.[27] Jordanian units that engaged the Israelis were quickly beaten back.[28] King Hussein of Jordan criticized Egyptian President Gamal Abdel Nasser for failing to come to Jordan's aid, and "hiding behind UNEF skirts".[29][30][31]
In May 1967, Nasser received false reports from the Soviet Union that Israel was massing on the Syrian border. Nasser began massing his troops in two defensive lines[32] in the Sinai Peninsula on Israel's border (May 16), expelled the UNEF force from Gaza and Sinai (May 19) and took up UNEF positions at Sharm el-Sheikh, overlooking the Straits of Tiran.[33][34] Israel reiterated declarations made in 1957 that any closure of the Straits would be considered an act of war, or justification for war,[35][36] and Nasser declared the Straits closed to Israeli shipping on May 22–23.[37][38][39] On May 30, Jordan and Egypt signed a defense pact. The following day, at Jordan's invitation, the Iraqi army began deploying troops and armored units in Jordan.[40] They were later reinforced by an Egyptian contingent. On June 1, Israel formed a National Unity Government by widening its cabinet, and on June 4 the decision was made to go to war. The next morning, Israel launched Operation Focus, a large-scale surprise air strike that was the opening of the Six-Day War.
Military preparation
Before the war, Israeli pilots and ground crews had trained extensively in rapid refitting of aircraft returning from sorties, enabling a single aircraft to sortie up to four times a day (as opposed to the norm in Arab air forces of one or two sorties per day). This enabled the Israeli Air Force (IAF) to send several attack waves against Egyptian airfields on the first day of the war, overwhelming the Egyptian Air Force, and allowed it to knock out other Arab air forces on the same day. This has contributed to the Arab belief that the IAF was helped by foreign air forces (see Controversies relating to the Six-Day War). Pilots were extensively schooled about their targets, and were forced to memorize every single detail, and rehearsed the operation multiple times on dummy runways in total secrecy.
The Egyptians had constructed fortified defenses in the Sinai. These designs were based on the assumption that an attack would come along the few roads leading through the desert, rather than through the difficult desert terrain. The Israelis chose not to risk attacking the Egyptian defenses head-on, and instead surprised them from an unexpected direction.
James Reston, writing in The New York Times on May 23, 1967, noted, "In discipline, training, morale, equipment and general competence his [Nasser's] army and the other Arab forces, without the direct assistance of the Soviet Union, are no match for the Israelis.... Even with 50,000 troops and the best of his generals and air force in Yemen, he has not been able to work his way in that small and primitive country, and even his effort to help the Congo rebels was a flop."[41]
On May 26, 1967, The CIA estimated:"The Israelis ... If they attack now they ... would still be able to drive the Egyptians away from the entrance to the Strait of Tiran, but it would certainly cost them heavy losses of men and materiel."[42]
On the eve of the war, Israel believed it could win a war in 3–4 days. The United States estimated Israel would need 7–10 days to win, with British estimates supporting the U.S. view.[43]
