On May 18, the UN caved in to Egyptian demands that the UN Emergency Force withdraw from the Sinai peninsula. Days later, on May 23, Egypt closed the Straits of Tiran to Israeli shipping, which cut off Israel's only southern port in Eilat from international shipping. Closing off the international waterway was an act of war.

On June 3, 100,000 Egyptians were massed in the Sinai, and another 110,000 ready for deployment. By the time Israel launched its first strikes against the Egyptian air force on June 5, some 200 Egyptian tanks were massed opposite Eilat and 60,000 Jordanian soldiers under Egyptian command were deployed along Israel's eastern borders. Although the war is named after Israel's lightning success, Egypt's casus belli took place in May.

Nathan Wolkovitz, Houston,