Of the many firsts created by Operation Desert Storm, keep this one in view through the fog of war and the rush of events: American combat troops now protect both Israelis and Arabs against a common enemy for the first time.

America, and Americans, are involved in the Middle East as never before.

America has embarked on a long, difficult and necessary course of action in combating Saddam Hussein's plans to destroy his neighbors. The Iraqi dictator's spurning of all peace efforts -- even one mounted by the Palestine Liberation Organization -- gave the American government and its allies no alternative.

As individuals, Americans suddenly find the emotional and intellectual distance from the Middle East shortened. Our television screens are filled with the images of citizens, soldiers and reporters from Israel, Saudi Arabia and the United States frantically pulling on gas masks and searching the skies for incoming Iraqi Scud missile warheads.

If any viewers missed the historical significance of watching a nation of Jews being forced to don gas masks in prime time, Baghdad Radio helpfully reminded them by boasting Saturday that Iraq would turn Tel Aviv into "a crematorium" through its missile attacks.

That boast makes clear the nature of Saddam Hussein's threat to Israel. What remained unclear after the first two nights of Scud attacks was the means at his disposal. That uncertainty shows that George Bush's decision to strike now at the Iraqi's chemical, biological and nuclear warfare capabilities was right.

In August, shortly after Iraq invaded Kuwait, the most authoritative intelligence assessment made in the U.S. government concluded that Saddam had not been able to develop a warhead for the Scud that would effectively deliver poison gas against his enemies.

But in October that assessment was suddenly changed. The intelligence community had detected significant Iraqi efforts to miniaturize the chemical warheads it does possess for use by artillery and to mount them on the Scuds. Senior administration officials and members of Congress were told that the Central Intelligence Agency and Defense Intelligence Agency could no longer stand by the August assessment.

Waiting would have simply given Saddam more time to work on the Scud warheads and ultimately to kill more Israelis, more Saudis and more Americans than he can today. The common assessment of the threat Saddam poses in Washington, Riyadh and Jerusalem underpins a three-way alliance that is temporary and asymmetrical but nonetheless dynamic.

The arrival of American technicians to operate Patriot anti-Scud missile batteries in Israel over the weekend is in its way as epochal as the stationing of 400,000 GIs in Saudi Arabia.

Israel too has traditionally rejected stationing American combat units on its soil. No nation likes to depend on foreigners for its defense. The Holocaust and the Zionist ethic of self-reliance heighten that refusal of depending on outsiders for Israelis.

As recently as October, State Department officials say, Israel rejected an American offer to send crews to operate the Patriot batteries. But in the face of Saddam's threat, that taboo has been dropped by the Israelis.

Although it exacts horrible costs that cannot be ignored or excused away, war is establishing an American credibility in the Middle East that diplomacy alone failed to achieve. A week of war has established a position of American evenhandedness and involvement absent from two decades of "the peace process."

Retaining and creatively employing that credibility once Saddam has been dealt with is the ultimate test confronting the Bush administration. America must be able then to show it can do more than kill Arabs as a way of establishing order in this conflict-filled region.

If the United States had not dealt with Saddam now, pressures would have grown for Israel to use its own weapons of mass destruction against the Iraqis and other Arabs in the near future. That is an outcome America has done well to avoid.

The sharp peacetime differences that separated Prime Minister Yitzhak Shamir and President Bush have given way to effective cooperation in wartime. Shamir's willingness to forgo immediate retaliation against Iraq reflects confidence in Bush's determination to remove the threat Baghdad poses to the region.

It is also a shrewd political decision by Shamir to build up credit with the United States to draw on in the broad Middle East peace effort that Washington is bound to attempt once the war against Saddam is out of the way. There could be no clearer sign that Desert Storm is proceeding well.