While working as national security advisor, Rostow became involved in setting the United States' posture towards Israel. Concerns about Israel's nuclear program were tabled by the United States during the build-up to the Six-Day War and its aftermath. Although he supported military and economic assistance to Israel, Rostow believed that increased public alignment between the two states could run counter to US diplomatic and oil interests in the region. Rostow considered President Gamal Abdel Nasser of Egypt to be a moderating force who through he talked belligerently of war, in fact kept the Arab-Israeli dispute "in the icebox". Rostow wrote in a memo advocating American economic aid to Egypt: "While no one likes the idea of paying off a bully, Nasser is still the most powerful figure in the Middle East...and has restrained wilder Arabs who have for a disastrous Arab-Israeli showdown". After reviewing the May 1967 report from the Atomic Energy Commission team that had inspected Dimona along with other intelligence, Rostow informed President Johnson that, though the team found no evidence of a nuclear weapons program, "there are enough unanswered questions to make us want to avoid getting locked in too closely with Israel. When Egypt remilitarized the Sinai in May 1967, Rostow did not support an Israeli strike against Egypt, instead writing "We sympathize with Eshkol's need to stop these raids and reluctantly admit that a limited attack on Syria may be his only answer". About the Egyptian remilitarization, Rostow wrote that goals of American policy must be "(a) prevent Israel from being destroyed (b) stop aggression, and (c) to keep U Thant out in front and stiffen his spine". In this regard, Rostow wrote it was essential to persuade the Israeli Prime Minister Levi Eshkol "not to put a match to this fuse". On 22 May 1967, Nasser further escalated the crisis by closing the Straits of Tiran to Israeli shipping, which was a provocation as Israel had always stated that they would go to war to keep the Straits of Tiran open.