Why did Gamal Abdel Nasser close the Gulf of Aqaba to Israeli shipping in 1967?

In May 1967, Egyptian President Gamal Abdel Nasser closed the Gulf of Aqaba to Israeli shipping primarily as a move to demonstrate leadership and support for his Arab allies, particularly Syria, amidst escalating regional tensions.12

For years, Nasser had faced criticism for his failure to aid other Arab states against Israel and for allegedly hiding behind the United Nations Emergency Force (UNEF) stationed in the Sinai Peninsula. Following increased Palestinian guerrilla incursions and Israeli retaliatory strikes, Nasser felt compelled to act to preserve his standing in the Arab world.12

On May 18, 1967, he requested the withdrawal of the UNEF from the Sinai border. When the UN interpreted this to include the removal of troops stationed at Sharm al-Shaykh, Egyptian forces moved to block the Gulf of Aqaba. This action effectively blockaded the southern Israeli port of Eilat, which Israel had previously declared would be considered a cause for war. This escalation directly preceded the Six-Day War, which began on June 5, 1967.12