As the United Arab Republic bullies the Middle East toward another war, it becomes increasingly clear that the Western powers will have to intervene to maintain the right of free navigation in the Strait of Tiran.

Israel cannot tolerate the blockade which UAR President Gamal Abdel Nasser has imposed on Israeli commerce in the Gulf of Aqaba. In destroying the precarious status quo that has prevailed since 1956, Nasser has cut off Israel's only outlet to Asia, East Africa, and the all-important oil of the Persian Gulf. His action is a violation of the right of free and innocent passage in the Strait of Tiran guaranteed under a 1956 U.N. resolution and an international convention. Israeli Prime Minister Levi Eshkol has declared the blockade an act of war, to which Israel will respond unilaterally if necessary.

If Israel acts alone, however, war is inevitable. Nasser cannot back down now without sacrificing forever his claim to leadership in the Middle East--and perhaps even his position in the United Arab Republic. His latest adventure was probably directed less at harming Israel than at reviving Arab unity, forcing Jordan and Saudi Arabia, his avowed enemies, to join him in an anti-Israeli coalition.

Only if the blockade is broken by a joint force of the Western maritime nations -- Britain, the Netherlands, Portugal, as well as the United States--can Nasser retreat. It would be foolhardy for him to provoke war with all these powers. The Soviet Union, which has encouraged him thus far, would not follow him into war against the U.S. in a situation where none of the Soviets' vital interests are involved. Nasser could undercut domestic opposition by launching another virulent propaganda campaign against "Zionist" elements in the U.S. and other Western countries.

This policy would have some costs for the U.S., even if Nasser backed down. For the Egyptian leader's indictment of the West would lose this country some good-will in the Middle East, and would force the U.S.'s best friends -- King Hussein of Jordan and King Faisal of Saudi Arabia -- to adopt a less friendly stance, at least in public.

Such costs, however, would be intangible and short-lived. The costs of war, particularly if the U.S. had to intervene to prevent an Arab victory, would be far greater. And it remains in the national interest of the U.S. to fulfill the commitment which this country made in 1956 to protect free passage in the Gulf and to defend that territorial integrity of all Middle Eastern states.

The U.S. has acted well in the crisis so far -- restraining the Israelis, working for time, and gaining support from as many maritime powers as possible. But the Strait must eventually be opened, and the "breathing spell" which the U.S. is now requesting in the U.N. will only allow Nasser to establish his aggression as the status quo. The U.S. should act now, before delay clouds the legitimacy of intervention, or causes Israel to act alone.