TO KEEP UP the United States' traditionally friendly connection to Israel has been one of the more vexing tasks of American policy in the Gulf. In an ultimate combat situation, Israel's formidable intelligence, planning and military resources make it a strength. But short of that point, it is a weakness: it ties Washington to unrequited Palestinian nationalism, an issue of tremendous volatility in the Arab world. American strategists have had to think out how they could neutralize the possible ways by which Saddam Hussein might exploit the antagonism felt to Israel by Washington's Arab partners. One response has been to advise Israel to take up a "low profile" -- to demonstrate it is no part of the anti-Iraq coalition. But a cynical President Hussein has refused to go along. He has sought, after the fact of his aggression, to pose as the champion of the Palestinians, and he has repeatedly and provocatively threatened to make Israel his first target in a war.

What to the United States is a vexing regional problem, however, is something different and more grave to Israel. Saddam Hussein's threats, politics and weapons constitute for it a real security danger. This has caught both the United States and Israel in a dilemma. The United States must be faithful to its friendship for Israel without affording Saddam Hussein a gratuitous political opening. Israel must play a discreet crisis role without endangering the current or future safety of its citizens, who sit within easy bomber and missile range of Iraq.

Earlier, an alarmed Israel went through a phase of speculating, partly out loud, on the conditions in which it might feel compelled to strike first. For Israel, preemption has a metaphysical cast relating to its survival as well as a political cast related to its defense. The United States necessarily took the view that Israeli preemption could shred the anti-Iraq coalition. But it responded all the same to Israel's expressed anxieties in a serious way -- with an acknowledgment of the danger, a reaffirmation of American concern and a fresh offer of crisis consultation. The recent Israeli emphasis on holding to a posture of deterrence, rather than preemption, suggests that Washington's message has gotten through to Jerusalem.

Whether the message also has gotten through to Baghdad is less certain. An Iraqi decision to initiate open conflict with a provocative attack on Israel, notwithstanding the punishment Iraq could expect in return, remains one frightening crisis scenario.

Between the United States and Israel major differences remain on the Palestine issue. Difficult as it may sometimes be to separate the two matters, however, no differences can be permitted on the issue of Israeli security. The Gulf crisis is posing a demanding test. So far the two countries are meeting it.