Multiple factors contributed to the conflagration which erupted between Israel and its neighbors that eventually became known as the 'Six-day War'. Accumulation of frequent unwelcome encounters and violent incidents between Israel and the Arab countries in the region during the mid-1960s caused the tensions between both parties to increase. The major causes of the 1967 war could be summarized as follows:

Expansion
On multiple occasions, the Israeli leadership expressed a sense of dissatisfaction with the land it seized in 1948. Israel had its eyes on the West Bank. According to the religiopolitical ideology of the Jewish state, the occupation of the West Bank would be the territorial fulfillment of the 'Biblical Land of Israel' as the West Bank is the modern location of the ancient lands of Judea and Samaria. So, there had to be further plans for expansion in order to occupy the rest of what they claimed to be their 'Promised Land' and waging a war was the best plan to achieve what they had in mind.

In addition, many Israelis believed that the Israel government did not cause the Arabs to suffer the type of defeat that would disincline them from instigating further engagements with the Jewish state in the previous conflict, the 1956 Suez War. David Ben-Gurion, the Israeli Prime Minister at that time, believed that another war would secure Israel's borders.3 According to the Israeli leadership, war was the best way to secure new, easily-defendable ceasefire lines through having geography act as boarders, and thus, moving the battle field into the Arab territories.

However, the Israeli propaganda of the threat of impending genocide and extermination at the hands of the neighboring Arabs was the Israeli justification for a so called 'preemptive' attack. Later, this statement was refuted by the Israeli leaders themselves.

General Matityahu Peled, one of the architects of the Israeli invasion, committed what the Israeli public considered blasphemy when he admitted the true thinking of the Israeli leadership: "The thesis that the danger of genocide was hanging over us in June 1967 and that Israel was fighting for its physical existence is only bluff, which was born and developed after the war".4

In addition, Israeli Air Force General Ezer Weizmann declared frankly that "there was never any danger of extermination". 5

Mordechai Bentov, a former Israeli Cabinet Minister, also dismissed the myth of Israel's imminent annihilation: "All this story about the danger of extermination has been a complete invention and has been blown up a posteriori to justify the annexation of new Arab territories". 6

Water
The issue of water rights had always raised tensions between Israel and the neighboring countries in the region. Before the 1967 war, Israel and the neighboring Arab states had occasionally fought over access to Jordan River waters, and these violent clashes increased in the Jordan River basin between 1951 and 1967.
During this period of time, nearly all of beneficiaries of the water from the Jordan River accepted the shares of water allotted for them by the Johnston Plan in 1955. However, Israel was secretly working on undermine the Johnston Plan and divert water from the Jordan River down to the Negev Desert for its 'National Water Carrier' [see map]. When this came to the knowledge of the Arabs in 1963, Egyptian President Nasser called for an Arab Summit. With this, the First Arab Summit took place in Cairo, January 1964, which resulted in the decision to stem the flow of water into Lake Tiberius (Sea of Galilee).7

The next year, the Arab states began the construction of the 'Headwater Diversion Plan,' which provided for the construction of a hydroelectric dam on the Yarmouk River between Syria and Jordan.  Once completed, the dam would divert the waters of the Banias Stream away from Lake Tiberius, to flow instead into a dam at Mukhaiba for Jordan and Syria.  The dam would also divert the waters of the Hasbani into the Litani, in Lebanon.8 Syria had begun earthworks to divert water away from Israel but these were bombed by Israel. The Israeli forces attacked the diversion works in Syria in March, May, and August of 1965, starting a prolonged chain of border violence that linked directly to the events leading to the 1967 war.

By mid-1967, Israel had depleted most of its own fresh water resources and started diverting the Jordan River waters at the expense of Jordan and Syria's use of the resource. During the war, the Israeli fighter jets damaged a half-completed dam on the Yarmouk River between Syria and Jordan and also the intake facilities for the East Ghor Canal (now called the King Abdallah Canal) along the Jordanian side of the Jordan River Valley.9

The constant struggle for the waters of the Jordan River was one of the major causes of the Six-day war in June 1967. Securing a constant supply of fresh water had been a goal of great magnitude for the early Zionists.10 Later, it became explicit policy for the State of Israel. The reason for this was obvious; unlimited access to fresh water was seen as a crucial condition for economic growth and security. Israel had its eyes not only on the Jordan River waters but also on the ground water basins in the West Bank, over which Israel took complete control after its occupation of the West Bank. To date, Israel still holds all water resources, as seen in Table (1.1), for the benefit of its expanding Jewish settlements, and denies the Palestinian people any access to them, leaving them suffering from water shortage, particularly during summer seasons.

Table (1.1): Available Water Resources in Mandate Palestine**

*Water consumption by Israeli settlers until their withdrawal from the Gaza Strip in 2005.
** Data Adapted from Israeli Ministry of Foreign Affairs, 1995.

Emergence of the 'Palestine Liberation Organization' (PLO)
Following the formation of the Palestine Liberation Organization (PLO) in 1964, war began to take on another form, for the Palestinian Resistance Movements added a new element to the conflict equation. Now the Palestinian people, the original inhabitants of the land, were speaking out for themselves and in direct confrontation with Israel. The PLO carried out 35 operations against Israel in 1965, increasing to 41 in 1966, and during the five months which preceded the war they carried out 37 operations.11 The first PLO operation against Israel was carried out by Fatah group on January 1, 1965, which targeted the Israeli National Water Carrier in Galilee. The majority of the PLO activities came from the northern and eastern borders and from the West Bank, which at the time was under Jordanian administration. These operations were not full-size operations; rather, they were small operations led by small groups using limited martial techniques.12 However, Israel was determined to wipe out the Palestinian resistance before it spread and became stronger, and saw war as an effective strategy to accomplish this.[For Operations conducted by the PLO against Israel, see Annex 1.]

Escalations in the Demilitarized Zone on the Syrian Front
In April 1967, Israel was conducting provocative operations over Syrian air-space which caused the two forces to clash. Israeli Prime Minister Levi Eshkol warned that Damascus would be occupied if necessary.13 These clashes between Israel and Syria were due to a dispute over cultivation rights in the demilitarized zone south-east of Lake Tiberius (Sea of Galilee).

On April 7, 1967, an aerial battle over the Golan Heights resulted in the loss of six Syrian MiG-21s to Israeli Air Force Dassault Mirage III's; Israeli jets deliberately flew low over the Syrian capital of Damascus to provoke the Syrians.14

A few days earlier, Syria attacked an Israeli tractor working in the area. The Israelis responded by sending in armor-plated tractors to continue the work, resulting in further exchanges of fire. Israeli aircraft dive-bombed Syrian positions with 250 and 500 kg bombs. The Syrians responded by shelling Israeli border settlements and Israeli jets answered back by bombing the village of Sqoufiye, destroying around 40 houses. Later on, Syrian shells started falling on the Israeli settlements in the Galilee area.15

Years later, Israeli Minister of Defense Moshe Dayan gave a different account of the reasons for war: "Along the Syria[n] border there were no farms and no refugee camps there was only the Syrian army... The kibbutzim saw the good agricultural land ... and they dreamed about it... They didn't even try to hide their greed for the land... We would send a tractor to plow some area where it wasn't possible to do anything in the demilitarized area and knew in advance that the Syrians would start to shoot. If they didn't shoot we would tell the tractor to advance further until in the end the Syrians would get annoyed and shoot. And then we would use artillery and later the air force also and that's how it was...The Syrians on the fourth day of the war were not a threat to us." 16

Es-Sumu' Massacre
Another incident that contributed to the escalation of tensions was Es-Sumu' Massacre. Es-Sumu', a Palestinian village of 1,200 houses and 5,000 inhabitants near Hebron (Al Khalil City), was under Jordanian control at the time the incident took place.17

Two days before the massacre happened, an Israeli border patrol hit a mine, killing three soldiers and injuring six others. Israel accused Es-Sumu' villagers of helping Palestinian Feda'yeen (Freedom fighters), and in a fierce operation, the village of Es-Sumu' was attacked in the morning of November 13, 1966. The Israelis, equipped with heavy artillery, took unarmed villagers by surprise in broad daylight.
"In Operation Zahal headed by Yitzhak Rabin, Israel's largest military operation since 1956, a force of around 3,000-4,000 soldiers backed by tanks and aircraft divided into a reserve force, which remained on the Israeli side of the border, and two raiding parties, which crossed into the West Bank. The larger force of eight Centurion tanks followed by 400 paratroopers mounted in 40 open-topped half-tracks and 60 engineers in 10 more half-tracks headed for Sumu', while a smaller force of 3 tanks and 100 paratroopers and engineers in 10 half-tracks headed towards two smaller villages, Khirbet El-Markas and Khirbet Jimba, on a mission to blow up houses."18
In Es-Sumu', Israeli soldiers completely demolished 125 houses, the village's only medical clinic, a 6-classroom school and a workshop. In addition, one mosque and 28 houses were damaged. 20 Jordanian army trucks, 2 Jordanian army jeeps and one civilian bus, were totally destroyed. One Jordanian army truck had been damaged by machine-gun fire, and in a flour mill, 2 explosive charges were found which had failed to detonate. Furthermore, Israeli troops killed 15 Jordanian soldiers and 3 civilians.19
No military response from Amman was announced. Palestinian anger and clashes with Jordanian security forces spread throughout the West Bank, especially in the city of Nablus, in the northern West Bank, where the army had to intervene.
On November 25, 1966, United Nations Security Council Resolution, number 228, was adopted unanimously deploring "the loss of life and heavy damage to property resulting from the action of the Government of Israel on 13 November 1966", censuring "Israel for this large scale military action in violation of the United Nations Charter and of the General Armistice Agreement between Israel and Jordan", and emphasizing "to Israel that actions of military reprisal cannot be tolerated and that if they are repeated, the Security Council will have to consider further and more effective steps as envisaged in the Charter to ensure against the repetition of such acts." 20

Economic Status in Israel
Israel's economic problems during that time have been sited by some historians as a major reason for desiring a war with the Arabs. A war would distract people's minds from unemployment and the low growth rate and would also bring in foreign money to boost the economy.21
During the 1950s and early 1960s, Israel had enjoyed a booming economy. In addition, Germany was providing Israel with money as compensation for the Nazis' crimes; by 1964 about $850 million were directed into the Israeli state treasury.22However, in the year 1966, Israel's economy went into a period of recession. The Israeli government announced economic restraint policies which caused a drastic decrease in Israel's large construction industry, the closing of many factories, and high unemployment.23Unemployment reached 12.8%, the highest since the establishment of the Israeli State.24Many businesses went bankrupt. Investment in construction fell by 30% and in industry by 20%, creating a sharp rise in prices and a lack of money in the hands of the working class and consumers.25 The growth rate was less than 1% and inflation was 8%.26
In response to this, the Israeli government denounced workers who demanded pay raises and praised a group of professors who agreed to accept lower wages.27The working class in Israel organized many strikes and large demonstrations in this period; Jewish workers arranged 277 strikes in 1966 alone.28
In February 1967, the Minister of Labor Yigal Allon reported to the Israeli Cabinet that the rate of unemployment had increased by 10%, and that the immigration to Israel had dropped: "for only 15,000 Jews have come to Israel in 1966, which meant that the Jews of the world have lost their enthusiasm towards the Land of Israel". 29On the other hand, the immigrants coming to Israel, expecting a better life, were faced with unemployment. There had to be another way to regain their attention. Therefore, Israel began to provoke the neighboring Arab countries to make the world believe that there was a serious threat that Israel might be attacked by its Arab neighbors, and thus, not taking the blame for starting a war in the region. Furthermore, a war would expand its borders and gain new sources of relatively cheap labor and new markets.
According to the Israeli Ministry of Foreign Affairs; "The Six Day War put an end to the recession, and began a period of economic growth. In 1969, growth was 12%, inflation fell to less than 4%, and even the unemployment rate, which in 1967 reached a high of more than 10%, fell below 4%."30