Syria, the most stridently hostile towards Israel of the Arab so-called "frontline" states in the years leading up to the 1967 war, was ruled by the Ba'ath party, which derived its ideology and institutions from the model of the European fascist states of the early twentieth century. The Ba'ath party was dominated by members of the Alawite religious minority (12% of the Syrian population) and maintained a shrill anti-Israel stance in large part to divert the discontent of Syria's Sunni majority. The president of Syria at the time was Nur al-Din al-Atasi, but future dictator Hafez Assad also wielded much influence as the defense minister and head of the air force. Syria was closely aligned with the Soviet Union and was a recipient of extensive Soviet aid.
In 1967, Syria had a population of 5.7 million. Its army numbered 100,000, and it possessed 550 tanks and 136 combat airplanes.
Prior to the Six Day War, a low intensity conflict festered between Israel and Syria. In 1964, a Syrian attempt to divert the headwaters of the Jordan River was halted by Israeli aerial bombardment. Syria also shelled Israeli communities from positions in the Golan Heights and allowed its territory to be used as a staging area for incursions into Israel by Palestinian terrorists.
On May 13, 1967, the Soviet Union relayed false information to Syria and Egypt that Israeli forces were massing on Syria's border. This prompted Syria and Egypt to activate their military pact and figured in Nasser's subsequent steps towards war. Syrian planes bombed northern Israel on June 5, the first day of the war. The following day, Syrian forces attacked the Israeli communities of Tel Dan, Kibbutz Shaar Yashuv and Ashmura but were repelled by Israeli forces. The Syrian air force unsuccessfully attempted to bomb oil refineries in Haifa. Israeli forces counter-attacked on July 9 and 10, driving the Syrians from the Golan Heights and bringing the Six Day War to a close. Estimated Syrian losses were 2500 killed, 5000 wounded, and 591 taken prisoner.
Asad, The Sphinx of Damascus, Moshe Maoz, 1988
Modern Syria, Moshe Maoz, 1999
Statistical Abstract / Central Bureau of Statistics, Syrian Arab Republic 1965-1998