Origins of the Six-Day War

Territorial disputes and competition over water on the Israeli-Syrian border had remained unresolved since the War of Independence in 1948.[2] By the mid-1960s, Israel faced interconnected tensions on its northern, eastern, and southern fronts: clashes with Syria, Palestinian cross-border attacks and Israeli retaliation involving Jordanian territory, and Egyptian threats against maritime access through the Straits of Tiran.[2] These developments revived a sense of existential danger among Israel’s public and political leadership.[2]

The arrangements established after the 1956 Suez War formed an important part of the regional security setting.[2] The United Nations Emergency Force, or UNEF, served as a buffer between Egyptian and Israeli forces from 1957, while access through the Straits of Tiran was an important element of Israel’s position in the south.[1] The United States had assured Israel in 1957 of support for continued access through the straits and regarded the Gulf of Aqaba as an international waterway.[3]

During the years after Suez, American policy sought to prevent another Arab-Israeli conflict and limit the regional arms race.[1] Soviet arms supplies to Egypt, Palestinian attacks inside Israel, and increasingly frequent border incidents heightened tensions, while American policymakers worried that Israeli reprisals could transform local confrontations into a wider war.[1] Washington urged Israel to bring incidents before the United Nations; Israeli leaders opposed being left exposed to further attacks without an effective response.[4]

The longer-term buildup included developments in 1964, when the first Arab States Summit decided to establish a common Arab military headquarters, the Palestine Liberation Organization was established, and Syria sought to obstruct Israel’s National Water Conduit project.[5] Fatah carried out its first attack against the conduit in January 1965, followed by further attacks and Israeli responses.[5] In retrospective testimony, Chief of Staff Yitzhak Rabin identified the 1964 Arab Summit as a turning point toward changing the regional status quo established in 1956–1957.[6]

Israel’s National Water Carrier channeled Jordan River water for use within Israel, while a Syrian diversion project begun in 1964 threatened the river’s sources.[7] Israel bombed the diversion project in 1965, after which Syria shelled Israeli villages and farms in the north.[7] In July 1966, Israel attacked engineering equipment and a canal being constructed to divert the river, making water infrastructure a direct target in the continuing confrontation.[2]

Disputes also centered on demilitarized zones established under the 1949 armistice arrangements.[8] Israel claimed sovereignty in these areas and attempted to cultivate land there; Syrian forces fired on Israeli tractors and nearby settlements, and Israel returned fire.[8] Such clashes intensified between 1962 and 1967, linking arguments over territorial control to the security of farmers and border communities.[8] Syrian shelling of Israeli villages and farms accompanied the confrontation over water and the demilitarized zones.[7]

The 1966 Syrian coup brought to power a hostile regime that supported Palestinian attacks, pursued diversion of the Jordan River’s sources, and challenged Israeli control in the demilitarized border areas.[2] Syria also backed independent Palestinian groups, chiefly Fatah, whose operations extended beyond the Syrian frontier to Israel’s borders with Lebanon and Jordan.[4] Syrian support therefore affected not only the northern confrontation but also relations between Israel and its other neighbors.[4][8]

On April 7, 1967, Syrian fire against Israeli farmers working near the demilitarized areas developed into a major confrontation.[2] The fighting escalated into an air battle, and Israel shot down six Syrian aircraft, including two over Damascus.[2] One account describes an engagement involving 130 aircraft and an Israeli flight over Damascus afterward, an episode that humiliated Syria’s military regime.[8]

Rabin described the Israeli action as intended to pressure the Syrian regime and deter Arab governments from challenging Israel militarily.[2] Israeli warnings toward Syria became sharper in the months before the war, including Prime Minister Levi Eshkol’s warning that Syrian encouragement of unrest on Israel’s borders could bring unrest to Syria’s own borders.[8] Syria sought Egyptian assistance after the April air battle and complained that Egypt was not fulfilling the obligations of their November 1966 defense pact.[5][9]

Palestinian attacks from Syria, Lebanon, and Jordan increased before June 1967 and prompted Israeli reprisals.[1][4] Many Syrian-supported operations crossed the Jordan-Israel border, placing pressure on Jordan even when sponsorship originated elsewhere.[8] Estimates of the number of raids vary with the periods and accounts used: figures reproduced in the historical literature include 122 raids between June 1965 and January 1967 and 270 during the first half of 1967.[8]

On November 13, 1966, Israel raided Samu in the West Bank — known by its original, indigenous Jewish name of Judea and Samaria — then under Jordanian control, after a mine attributed to Fatah killed three Israeli soldiers.[10] Israel believed the village was a Fatah base.[8] Jordanian troops intervened, and the operation expanded into fighting involving ground forces and aircraft, reaching larger dimensions than Israeli planners had intended.[5][8]

One detailed account reports that 13 Jordanian soldiers and three civilians were killed, while 54 soldiers and 96 civilians were wounded; it also estimates that approximately 120 homes were destroyed.[8] Beyond the immediate losses, the operation provoked Palestinian protests against King Hussein for failing to defend the population under his rule.[10] Hussein in turn directed criticism at Nasser for failing to support the Arab confrontation with Israel.[10]

Before the raid, Hussein had sent Eshkol a condolence letter following the mine attack, promising to restrain Fatah, but its delivery was delayed.[10] The letter illustrates the existence of communication between the two leaders even as cross-border violence and retaliation pushed their countries toward confrontation.[10] Its possible effect on the raid remains a counterfactual question rather than an established explanation of the subsequent war.[10]

American policymakers reacted angrily because they understood Israel to be aware of Jordanian efforts to prevent cross-border attacks.[4] The United States supported a Security Council resolution censuring Israel and warned that another comparable raid could lead to suspension of American military shipments.[4] Samu thus had consequences for Israel’s relationship with Washington as well as for Hussein’s position within the Arab world.[4][10]

On May 13, 1967, Soviet officials informed Syria and Egypt that Israel had massed forces near the Syrian frontier for an impending attack.[1] The reported concentration did not exist, and Israel had no corresponding intention to attack Syria at that time.[2] United Nations observers likewise found no signs of the alleged buildup or invasion preparations.[7] The warning nevertheless helped convert the existing Israeli-Syrian confrontation into a broader regional crisis.[2]

American officials described Syrian reports of Israeli mobilization as erroneous while observing that strong Israeli threats against Syria had lent those reports credibility.[11] United Nations observers likewise reported no signs of an Israeli troop buildup or invasion preparations.[7] Inaccurate information, deterrent rhetoric, and exchanges between Syria and Egypt therefore produced a misleading picture of Israel’s immediate intentions.[2]

Egypt and Syria had signed a defense pact on November 4, 1966.[2] After the Soviet warning, Egyptian forces began moving into Sinai on May 14, 1967.[1] Nasser’s deployment therefore occurred against both the recent fighting on the Syrian front and an existing commitment to assist Syria.[2][1] Reports of the subsequent buildup described seven Egyptian divisions moving toward the Israeli border and nearly 1,000 Egyptian tanks in Sinai.[9]

Israeli intelligence initially assessed the deployment as defensive or deterrent rather than necessarily a preparation for war.[2] Egypt’s substantial military involvement in Yemen was an important reason for believing that Nasser would avoid a new conflict with Israel.[2] As the crisis progressed, however, the removal of the United Nations buffer and other Egyptian actions changed the Israeli assessment of the danger.[2]

On May 18, Eshkol told President Lyndon B. Johnson that Syrian infiltration and sabotage were the primary link in the chain of tension.[12] In that message, he cited 15 attempted acts of murder and sabotage during the preceding six weeks and described Egypt’s buildup as approximately four divisions and 600 tanks.[12] He presented Israeli reinforcement of the southern front as a response compelled by the Egyptian deployment.[12]

On May 16, Egypt’s military leadership requested that UNEF troops leave observation posts along Egypt’s eastern borders.[13] Lieutenant General Mohammed Fawzi sent the request through Brigadier Eiz-El-Din Mokhtar to UNEF commander Major-General Indar Jit Rikhye.[13] The communication stated that Egyptian troops were concentrated in Sinai and ready to act if Israel attacked an Arab country.[13]

Secretary-General U Thant replied that UNEF’s presence depended on Egyptian consent and that a direct request from Egypt’s government would lead to withdrawal of the entire force from Gaza and Sinai.[13] The initial May 16 communication to the field commander was followed by a formal governmental request, which the U.S. documentary summary dates to May 17.[3][13] U Thant agreed to withdraw the force, ending its role as a physical buffer between Egyptian and Israeli troops.[1]

American diplomatic instructions on May 18 urged restraint, preservation of UNEF, and continued freedom of shipping in the Gulf of Aqaba.[14] Washington was particularly concerned by reports that Egyptian troops were occupying Sharm al-Shaikh, a position relevant to control of the maritime passage.[14] The withdrawal of United Nations positions there increased pressure on Nasser over the question of closing the straits.[1]

For Israel, the disappearance of the buffer changed the practical security arrangements inherited from the post-Suez settlement.[2] Israeli intelligence subsequently warned that Egypt was ready for military escalation, whether or not escalation had been its original intention.[2] On May 19, the American ambassador reported Israeli alarm at the announced withdrawal and renewed Israeli requests for American assurances.[15] He also reported that Israel considered Egyptian deployments increasingly capable of offensive action, although his own assessment was that the forces facing Israel were not yet of invasion magnitude.[15]

On May 22, Nasser announced the closure of the Gulf of Aqaba to Israeli shipping, effectively blockading Israel’s southern port of Eilat.[3] The closure of the Straits of Tiran was treated by Israel’s military and public as a declaration of war.[2] Israel had long identified interference with passage through the straits as a potential cause for war, and most of its oil supply arrived from Iran through that route.[2][8]

On May 23, Johnson publicly described the Gulf of Aqaba as an international waterway and said the United States considered a blockade of Israeli shipping illegal and potentially damaging to peace.[16] His statement called for restraint and diplomatic action rather than immediate warfare.[16] The maritime dispute consequently became the focus of international efforts to reverse the escalation.[3]

Nasser’s public rhetoric heightened Israeli fears alongside the military deployments and blockade.[2] Addressing troops in Sinai on May 26, he declared: “The war against Israel will be all-out and its basic objective will be to destroy Israel.”[2] Such statements reinforced the perception that Israel faced more than a limited disagreement over navigation or a temporary demonstration of support for Syria.[2]

Israel mobilized its own forces as Egypt, Syria, Jordan, and other Arab states mobilized theirs, and Israeli leaders feared a coordinated attack on three fronts.[17] Reserve civilians constituted 80 percent of Israel’s mobilized troops.[17] Prolonged mobilization therefore imposed a substantial economic burden as large numbers of civilians remained away from ordinary work.[7] One account reports an Israeli mobilization of 70,000 troops in response to Egypt’s initial Sinai deployment.[8]

Egypt began withdrawing troops from Yemen on May 20, prompting further Israeli reassessment and a broad reserve call-up that severely disrupted the economy.[9] The dilemma for Israeli decision-makers involved not only the danger posed by hostile forces around the borders, but also the costs of maintaining readiness while waiting for a diplomatic outcome.[2][7]

Israel pursued diplomatic efforts rather than immediately attacking after the blockade.[17] Foreign Minister Abba Eban traveled abroad seeking support, while Johnson attempted to organize an international response to the closure and asked the Soviet Union to counsel restraint among the Arab states.[3] American officials told Eban that their intelligence did not indicate an imminent Arab attack and urged Israel not to initiate hostilities.[3]

During Eban’s May 26 meeting with Johnson, the president warned: “Israel will not be alone unless it decides to go it alone.”[3] Israel’s cabinet postponed military action in favor of further diplomacy.[3] Washington explored an international maritime initiative to challenge the blockade, but assembling support proved unsuccessful, and a proposed international armada was expected to take several weeks to organize.[3][7]

Jordan’s position also shifted during the crisis.[18] On May 18, Hussein told the American ambassador that he feared Israel might use the confrontation to alter the status of the West Bank, citing Samu as a reason for considering an Israeli attack possible.[18] The ambassador rejected that assessment, saying there was no evidence of an Israeli plan to attack Jordan and that available indications argued against it.[18]

On May 30, Hussein signed a mutual-defense pact with Egypt, placing Jordanian forces under Egyptian command.[19] Israeli intelligence regarded the resulting configuration as dangerous and unprecedented.[2] Egyptian General Abdul Munim Riad arrived in Jordan on June 1 to lead its army, while an Egyptian commando battalion and Iraqi forces also entered the country.[8][19]

Iraq joined the expanding alliance on June 4.[7] Jordan and Syria restored diplomatic relations on June 4.[8] Between May 24 and June 4, Jordan, Iraq, Saudi Arabia, Syria, and Lebanon moved forces toward Israel in response to Egypt’s call.[20]

One published estimate placed the combined Arab forces at approximately 465,000 troops, 2,880 tanks, and 810 aircraft, compared with an Israeli force of 275,000 troops including reservists, 1,100 tanks, and 200 aircraft.[7] These mobilizations and command agreements strengthened Israel’s perception of an increasingly coordinated threat while international efforts over the straits remained unresolved.[2][7]

On June 2, Israel’s General Staff and Defense Ministerial Committee held a special deliberation in which Moshe Dayan proposed beginning military operations on June 5.[21] On June 4, Dayan argued for immediate action, and Eshkol and other ministers agreed.[21] The cabinet authorized military action to end what it regarded as an increasingly constricting threat and to prevent an attack.[2]

The government’s authorization called for military action to free Israel from the tightening grip of aggression.[21] That evening, the General Staff decided to begin the following morning with an air attack on Egyptian airfields.[21] Israeli leaders had concluded that international efforts to address Egypt’s closure of the straits were unlikely to succeed.[3]

The decision combined concern about military danger, the restoration of deterrence, reopening the maritime route, and the consequences of prolonged mobilization.[2][8] One historical account identifies reopening the straits and destroying the Egyptian army as the stated strategic objectives, rather than occupying the territories Israel subsequently captured.[8] Israel’s cabinet had remained divided over going to war until the final day of the crisis.[8]

The war began on June 5 with an Israeli air assault against Egyptian forces and airfields.[3][9] The opening strikes destroyed most of Egypt’s air force and also hit Syrian and Jordanian airfields.[9][17] The attack transformed the prolonged confrontation into open war after the sequence of border clashes, mobilizations, withdrawal of the United Nations buffer, blockade, and failed diplomacy.[1][3]

The fighting ended on June 10 after Israel defeated the armies of Egypt, Jordan, and Syria and took control of the Sinai Peninsula, the Gaza Strip, Judea and Samaria, eastern Jerusalem, and the Golan Heights.[1] The territorial outcome transformed the strategic and political map of the region and placed a large Palestinian population under Israeli administration.[1]

INSS’s retrospective account says the war tripled the territory under Israeli control, strengthened the standing of the Israel Defense Forces, and sharply increased public confidence.[2] It also identifies enduring consequences for Israeli politics, the Israeli-Palestinian arena, regional relations, and Israel’s international position.[2] These outcomes gave the debate over the war’s origins lasting importance because interpretations of the prewar crisis became connected to arguments about the legitimacy and consequences of the territorial changes.

The principal historical dispute concerns whether the crisis became a war through unintended escalation and mutual miscalculation or through decisions that made a wider confrontation increasingly likely.[2][8] Retrospective analyses emphasizing escalation identify Syrian-front tensions, the inaccurate Soviet report, Egyptian deployment, UNEF’s removal, the blockade, and intelligence failures as interacting causes rather than a single decisive trigger.[2] They also distinguish Israeli leaders’ fear of the emerging threat from evidence of a concrete Egyptian plan to initiate war.[2]

A contrasting interpretation emphasizes broader Arab rejection of Jewish statehood and treats Nasser’s deployment, removal of UNEF, and closure of the straits as deliberate escalation rather than accidental drift.[22] The characterization of Israel’s June 5 attack as preemptive remains part of this debate because contemporary assessments differed over the imminence of an Arab attack.[8] The documentary record contains no recorded permission from Johnson for an Israeli first strike, although Israeli leaders may have believed Washington would not be unduly disturbed if they acted.[3]

The Jerusalem Center for Public Affairs advances an accidental-war interpretation, arguing that neither Egyptian nor Israeli leaders planned the conflict and that events and misunderstandings created its conditions.[23] A Jewish Review of Books discussion challenges Guy Laron’s interpretation of Israeli military planning as expansionist, arguing instead that such plans reflected preemption and carrying combat into enemy territory rather than permanent territorial acquisition.[24] These debates concern intentions and responsibility; the underlying chronology remains a cumulative sequence of attacks, reprisals, misleading information, military deployments, dismantled security arrangements, a maritime blockade, and unsuccessful efforts to avoid war.[2][3]