Today, the outskirts of Baghdad, Iraq. Tomorrow, downtown Damascus, Syria?

That's not to be taken quite literally, but neither can a secret surprise assault on Syrian missile sites in Lebanon or on Syria itself be easily dismissed as an encore to Israel's brazen invasion of Saudi Arabian and Jordanian irspace en route to the devastating bombing of Iraq's nuclear facilities.

Sources in a position to know the thinking of the Israel government put high on the list of useful byproducts from the attack on Iraw this plain message to Syria's President Assad: Don't drag out the Lebanese missile crisi; Israel has few options when diplomacy fails.

"If Assad thinks he can continue endlessly reinforcing the missile installations in Lebanon and confront us with a fait accompli ," says one Israeli, "this tells him our patience isn't endless. The Iraquis ignored our diplomatic efforts. I would hate to see the Syrians make the same mistake."

One can take that as a bluff. And it's certainly not a prediction that the Lebanese mediating mission of special U.S. envoy Philip Habib is necessarily a casualty of the Israeli raid on Baghdad -- though the working conditions for any peace initiative in the Arab-Israeli conflict have hardly been improved.

Rather, it is fresh confirmation (if such were needed) of a uniquely Israeli attitude toward the norms of international conduct and the diplomatic process -- a cast of mind that finds particularly virulent expression in the so-who-cares-what-you-think? attitude of the incumbent government of Prime Minister Menachem Begin. Some would call it chutzpah, admiringly. Others in Congress and elsewhere apparently regard it as no more than the logical consequence of Israel's strategic vulnerability.

But in the affair of the Iraqui reactor, the Israeli attack has the look of lawlessness. In its effect, what's more, it is arguably subversive to Mideast stability and dangerous to Israel as well as to its neighbors. It is also a clear challenge to the authority and credibility of the Reagan administration's new and largely untested capacity to conduct foreign policy.

The Reagan administration is not the first to encounter it. The bright prospects for Jimmy Carter's Camp Dvid accords -- the Framework for Peace -- were almost instantly blown away by Begin's quick reassertion of Israeli rights to expand and accelerate the settlement of the occupied West Bank.

It may take weeks -- or months, if Begin wins reelection -- to determine to what extent the attack on the Iraqi reactor will undercut the Reagan administration's own grand strategy for achieving peace and security in the Middle East. What seems safe to say now is that every crucial element, save one, in the Reagan policy has been damaged by the latest Begin display of contempt for the Reagan administration's ambitions and sensitivities.

The ironic exception is the proposed AWACS sale to Saudi Arabia. It has not escaped the notice of the Saudis that the Israeli penetration of Saudi airspace, which escaped detection by American AWACS otherwise occupied at the time. constitutes a persuasive argument for having early-warning airborne radar systems of their own.

For the rest of the Haig/Reagan strategy, the repercussions can only be regarded as adverse. Egypt's Anwar Sadat, having been Begin's visitor only a few days before the attack, looks the fool in the eyes of precisely those moderate Arabs with whom he is already in deep trouble for playing the American game at Camp David.

The Saudis have reason now to be less receptive to the administration argument that the Soviets, not the Israelis, are the real threat to the region's security. The argument becomes very nearly ludicrous when you consider that, in the thinking of the Reagan high command, Saudi Arabia and Egypt, together with Israel , are supposed to be the main elements in a sought-after "strategic consensus" against communist encroachment.

Yet another significant element in the administration approach was to be a quiet effort to lure Iraq away from Soviet influence and into the moderate Arab camp. Something of the same slow weaning away of Syria from Soviet client-state status was another goal. If these evolutions ever had a chance, most experts believe they have been knocked in the head for now.

Israel officials profess unconcern. "After any successful operation, there is always a little fever," says one. "But the patient will be better for it in the end." Perhaps so in the case of the Israeli "patient" -- for a time. But for the longer haul, the Arab diplomats I've talked with see it otherwise: as a heavy blow to the peace process and a decisive test of American willingness to "stand up" to Israel.

How forcefully that willingness is conveyed, not just immediately (by holding up delivery of four F16s to Israel) but in a sustained way, will determine how successfully the Reagan administration can work the Arab world back into its grand design for the Middle East -- and Persian Gulf -- security.