In addition to sponsoring attacks against Israel (often through Jordanian territory, much to King Hussein's chagrin), Syria also began shelling Israeli civilian communities in north-eastern Galilee, from positions on the Golan Heights, as part of the dispute over control of the Demilitarized Zones (DMZs), small parcels of land claimed by both Israel and Syria.

In 1966, Egypt and Syria signed a military alliance, initiated for both sides if either were to go to war. According to Egyptian Foreign Minister Mahmoud Riad, Egypt had been persuaded to enter into the mutual defence pact by the Soviet Union. From the Soviet perspective the pact had two objectives:

To reduce the chances of a punitive attack on Syria by Israel

To bring the Syrians under what they considered to be Egyptian President Gamal Abdel Nasser's moderate influence.

Nasser's pan-Arabism had numerous supporters in Jordan (in spite of Hussein, who felt it threatened his authority); and so, on May 30, Jordan signed a mutual defense treaty with Egypt, thereby joining the military alliance already in place between Egypt and Syria. President Nasser, who had called King Hussein an "imperialist lackey" just days earlier, declared: "Our basic objective will be the destruction of Israel. The Arab people want to fight."

At the end of May 1967, Jordanian forces were given to the command of an Egyptian General Abdul Munim Riad. On the same day, Nasser proclaimed: "The armies of Egypt, Jordan, Syria and Lebanon are poised on the borders of Israel ... to face the challenge, while standing behind us are the armies of Iraq, Algeria, Kuwait, Sudan and the whole Arab nation. This act will astound the world. Today they will know that the Arabs are arranged for battle, the critical hour has arrived. We have reached the stage of serious action and not of more declarations." Israel called upon Jordan numerous times to refrain from hostilities. Hussein, however, was caught on the horns of a galling dilemma: allow Jordan to be dragged into war and face the brunt of the Israeli response, or remain neutral and risk full-scale insurrection among his own people. Army Commander-in-Chief General Sharif Zaid Ben Shaker warned in a press conference that "If Jordan does not join the war a civil war will erupt in Jordan".


Israel's own sense of concern regarding Jordan's future role originated in Jordanian control of the West Bank. This put Arab forces just 17 kilometres from Israel's coast, a jump-off point from which a well coordinated tank assault would likely cut Israel in two within half an hour. Such a coordinated attack from the West Bank was always viewed by the Israeli leadership as a threat to Israel's existence. Although the size of Jordan's army meant that Jordan was probably incapable of executing such a maneuver, the country was perceived as having a history of being used by other Arab states as staging grounds for operations against Israel; thus, attack from the West Bank was always viewed by the Israeli leadership as a threat to Israel's existence. At the same time several other Arab states not bordering Israel, including Iraq, Sudan, Kuwait and Algeria, began mobilising their armed forces.

Jordan was reluctant to enter the war. Some claim that Nasser used the obscurity of the first hours of the conflict to convince Hussein that he was victorious; he claimed as evidence a radar sighting of a squadron of Israeli aircraft returning from bombing raids in Egypt which he claimed to be Egyptian aircraft en route to attacking Israel. One of the Jordanian brigades stationed in the West Bank was sent to the Hebron area in order to link with the Egyptians. Hussein decided to attack.

Prior to the war, Jordanian forces included 11 brigades totaling some 55,000 troops, equipped by some 300 modern Western tanks. Of these, 9 brigades were deployed in the West Bank and 2 in the Jordan Valley. The forces were organized in 4 divisions, one of them being the elite armored 40th. The Jordanian ground army was relatively well-equipped and well-trained. Furthermore, Israeli post-war briefings claimed that the Jordanian staff acted professionally as well, but was always left "half a step" behind by the Israeli moves. The Royal Jordanian Air Force, however, consisted of only about 20 Hawker Hunter fighters, obsolete by all standards.

Israeli Central Command forces consisted of five brigades. The first two were permanently stationed near Jerusalem and were called the Jerusalem Brigade and the mechanized Harel Brigade. Mordechai Gur's 35th paratrooper brigade was summoned from the Sinai front. An armored brigade was allocated from the General Staff reserve and brought to the Latrun area. The 10th armored brigade was stationed north of Samaria. The Israeli Northern Command provided a division (3 brigades) led by Maj. Gen. Elad Peled, which was stationed to the north of Samaria, in the Jezreel Valley.

The IDF's strategic plan was to remain on the defensive along the Jordanian front, to enable focus in the expected campaign against Egypt. However, on the morning of 5 June, Jordanian forces made thrusts in the area of Jerusalem, occupying Government House used as the headquarters for the UN observers and shelled the Israeli (western) part of the city. Units in Qalqiliya fired in the direction of Tel-Aviv. The Royal Jordanian Air Force attacked Israeli airfields. Both air and artillery attacks caused little damage. Israeli units were scrambled to attack Jordanian forces in the West Bank. In the afternoon of that same day, Israeli Air Force (IAF) strikes destroyed the Royal Jordanian Air Force. By the evening of that day, the Jerusalem infantry brigade moved south of Jerusalem, while the mechanized Harel and Gur's paratroopers encircled it from the north.

On June 6, the Israeli units attacked: The reserve paratroop brigade completed the Jerusalem encirclement in the bloody Battle of the Ammunition Hill. The infantry brigade attacked the fortress at Latrun capturing it at daybreak, and advanced through Beit Horon towards Ramallah. The Harel brigade continued its push to the mountainous area of north-west Jerusalem, linking the Mount Scopus campus of Hebrew University with the city of Jerusalem. By the evening, the brigade arrived in Ramallah. The IAF detected and destroyed the 60th Jordanian Brigade en-route from Jericho to reinforce Jerusalem.


In the north, one battalion from Peled's division was sent to check Jordanian defenses in the Jordan Valley. A brigade belonging to Peled's division captured Western Samaria, another captured Jenin and the third (equipped with light French AMX-13s) engaged Jordanian M48 Patton main battle tanks to the east.

On 7 June heavy fighting ensued. Gur's paratroopers entered the Old City of Jerusalem via the Lion's Gate, and captured the Western Wall and the Temple Mount. The Jerusalem brigade then reinforced them, and continued to the south, capturing Judea, Gush Etzion and Hebron. The Harel brigade proceeded eastward, descending to the Jordan River. In Samaria, one of Peled's brigades seized Nablus; then it joined one of Central Command's armored brigades to fight the Jordanian forces which held the advantage of superior equipment and were equal in numbers to the Israelis.

Again, the air superiority of the IAF proved paramount as it immobilized the enemy, leading to its defeat. One of Peled's brigades joined with its Central Command counterparts coming from Ramallah, and the remaining two blocked the Jordan river crossings together with the Central Command's 10th (the latter crossed the Jordan river into the East Bank to provide cover for Israeli combat engineers while they blew the bridges, but was quickly pulled back because of American pressure).

In a 16 August, 1995 interview for Israel Radio, Aryeh Yitzhaki of Bar-Ilan University, who had worked previously in the IDF history department, accused IDF units of killing up to 1,000 Egyptians who had abandoned their weapons and fled into the desert during the war. The allegations received widespread attention in Israel and throughout the world. However, it emerged subsequently that Yitzhaki was a member of Rafael Eitan's Tsomet Party and former employer Meir Pa'il speculated that Yitzhaki had an ulterior motive in seeking to divert public attention away from revelations by retired general Arye Biro concerning his involvement in the killing of 49 POWs in the 1956 war.

Although Yitzkhaki’s claim that up to 1,000 prisoners had been killed was not substantiated, in an ensuing highly-controversial national debate in Israel, more soldiers came forward to say that they had witnessed the execution of unarmed prisoners and a long-suppressed public reckoning began. Israeli military historian Uri Milstein was reported as saying that there were many such incidents in the war: "It was not an official policy, but there was an atmosphere that it was okay to do it. Some commanders decided to do it; others refused. But everyone knew about it".

A June 11, 1967 general-command IDF order specifically forbade killing prisoners, clarifying the official Israeli position. However, no official Israeli documents that would allow the scale of the killings to be accurately assessed have been released.

According to a New York Times report of 21 September, 1995 the Egyptian government announced that it had discovered two shallow mass graves in the Sinai at El Arish containing the remains of 30-60 Egyptian prisoners shot by Israeli soldiers during the 1967 war. Israel reportedly offered compensation to the families of the victims.

According to Israeli official records, 4,338 Egyptian soldiers were captured by IDF. Only 11 Israeli soldiers were taken prisoners by Egyptian forces. Exchanges of those prisoners were completed on 23 January, 1968.

Some Arabs believe that the United States and Britain provided active support for the Israeli Air Force. Claims of American and British combat support for Israel began on the second day of the war. Radio Cairo and the government newspaper Al-Ahram made a number of claims, among them: that U.S. and British carrier-based aircraft flew sorties against the Egyptians; that U.S. aircraft based in Libya attacked Egypt; and that U.S. spy satellites provided images to Israel. Both Syria and Jordan broadcast similar reports on Radio Damascus and Radio Amman. These claims were also repeated by Egyptian President Gamal Abdel Nasser in his June 9 resignation speech (his resignation was not accepted).

Both London and Washington strongly denied these claims, and no evidence has ever corroborated them. In American and British government circles, these accusations quickly became known as 'the big lie.'

Nonetheless, these claims, that the Arabs were fighting the Americans and British rather than Israel alone, took hold in the Arab world. According to Israeli historian Elie Podeh: "All post-1967 Egyptian history textbooks repeated the claim that Israel launched the war with the support of Britain and the United States. The narrative also established a direct link between the 1967 war and former imperialist attempts to control the Arab world, thus portraying Israel as an imperialist stooge. The repetition of this fabricated story, with only minor variations, in all history school textbooks means that all Egyptian schoolchildren have been exposed to, and indoctrinated with, the collusion story." A British guidance telegram to Middle East posts concluded: "The Arabs' reluctance to disbelieve all versions of the big lie springs in part from a need to believe that the Israelis could not have defeated them so thoroughly without outside assistance."

Historians such as Michael Oren have argued that by falsely accusing the United States and Britain of directly helping the Israelis the Arab leaders were attempting to secure active Soviet military assistance for themselves. The Soviets, however, knew that these claims of foreign assistance to Israel were groundless and notified Arab diplomats in Moscow of that fact. Yet even though the Soviet government disbelieved these accusations, Soviet media continued to quote them, thereby strengthening the credibility of the reports. In reaction to these claims, Arab oil-producing countries announced an oil embargo.

In a 1993 interview, U.S. Secretary of Defense Robert McNamara revealed that the U.S. 6th Fleet Carrier battle group, on a training exercise near Gibraltar was re-positioned towards the eastern Mediterranean to defend Israel if necessary, causing a crisis between the US and USSR. McNamara did not explain how the crisis was resolved.

In his book Six Days, BBC journalist Jeremy Bowen claims that during the crisis, Israeli ships and planes carried British and American military arms reserves from British soil.