ISRAEL'S PRIME MINISTER, Yitzhak Shamir, has underlined the central consideration that ought to guide American arms sales to countries in the Middle East and other troubled regions. Speaking in a Wall Street Journal interview of proposed American sales to Saudi Arabia, he said: "Until an Arab country is active in peace with Israel, it shouldn't get sophisticated U.S. weapons." The notion of linking arms to peace, or to a diplomacy seeking peace, seems to us exactly the right test to apply to commerce in arms. The trouble with Mr. Shamir's formulation is that it contains the potential for embarrassment of his own government.

That government is currently stymying a proposal that has much international support, including formal American support: an international peace conference. Each concerned government has its own view of such a conference, but basically all of them are prepared to go forward. Whether a conference would produce a good result is necessarily a matter of doubt and speculation. But that the United States has a paramount interest in carefully exploring every reasonable opening is undeniable. Saudi Arabia and other "moderate" Arabs are eager for a conference. Israel resists, or rather, Mr. Shamir's half of Israel's strangely organized government resists, and his half blocks the other half, which is ready. The American government, deferring to Israel, has suspended almost any active effort to organize a conference pending an easing of Israel's objections to it.

We are not here claiming that the United States should put the squeeze on Israel and deny sophisticated arms until Israel joins the parade to a conference. But surely it is relevant to American deliberations on selling arms to Saudi Arabia and like Arab countries that the Saudis are eager, even desperate, to support a serious diplomatic proposal that the United States sanctions and that Mr. Shamir rejects. The Saudis are friends who live in dangerous parts; they have a claim to buy weapons apart from the Arab-Israeli dispute. But to deny them arms when they meet in an approved American fashion a very fair and reasonable Israeli standard to become "active in peace with Israel" -- even as Israel blocks the calling of a conference and rejects the parallel opportunity to become "active in peace with Saudi Arabia" -- is all wrong.