Jordan was a reluctant belligerent in the third Arab-Israeli war. The principal decision maker on the Jordanian side was King Hussein bin Talal who had ascended the Hashemite throne in 1953 at the tender age of eighteen. Hussein was the heir to a Hashemite legacy of moderation and pragmatism towards the Zionist movement that went back to his grandfather, King Abdullah I, the founder of the Hashemite Kingdom of Jordan. Hussein was also the heir to an even older Hashemite legacy of leadership in the struggle for Arab independence and unity. This legacy went back Hussein's great-grandfather, Hussein the Sharif of Mecca, who staged the Arab Revolt against the Ottoman Empire in World War I. King Hussein's foreign policy was essentially a balancing act between the conflicting claims of Arab nationalism and coexistence with Israel. During the Suez Crisis of 1956, Hussein's commitment to Arab nationalism led him to side with Egypt against Israel. He even offered to open a second front against Israel, but President Gamal Abdel Nasser dissuaded him. After Suez, the pragmatic strand in Hussein's foreign policy came to the fore, and in 1963 he initiated a secret dialogue with Israel's leaders. This dialogue across the battle lines enabled Jordan and Israel to reach a modus vivendi, a state approaching de facto peace.
Jordan's entry into the war against Israel in 1967 alongside the radical Arab regimes calls for an explanation. The explanation offered here is that an ill-considered Israeli military attack upset the delicate balance and launched Jordan on the slippery slope that led to its participation and disastrous defeat during the Six-Day War. It is essential to distinguish Israel's intentions from King Hussein's perceptions. Israel had no intention and no plan to attack Jordan. Hussein misperceived Israel's intentions and these misperceptions guided, or rather misguided, his subsequent policy. The attack destroyed Hussein's faith in Israel's peaceful intentions, although Israel harboured no plans of aggression. It left him feeling that his country was isolated and vulnerable and drove him into a rapprochement with Egypt within the framework of the United Arab Command (which had been set up in 1964) in order to counter the perceived Israeli threat. The alliance with Egypt, however, quickly embroiled Hussein in a war that he neither wanted nor anticipated.