The decision by Secretary of State James A. Baker III to temporarily suspend U.S. dialogue with the PLO reinforces secret efforts by Prime Minister Yitzhak Shamir to construct a ''unity'' government that could finally go to the peace table with the Palestinians.

As usual, things are not quite what they seem in the Middle East. Even though the U.S.-PLO breakdown will provoke what a Bush administration official calls a ''war-building'' crisis, it makes negotiations politically more feasible for Shamir. Although he announced formation on Friday of a dangerously right-wing coalition to rule Israel, the conservative Likud prime minister has in mind a wholly different government, which again would share power with Labor.

Thus, the intercepted Palestinian terrorist raid on the Tel Aviv beaches, which would have yielded a gruesome harvest had it succeeded, may ironically turn out to be a harbinger of change for the better. If a firestorm in the Mideast can be avoided now, the thwarted terrorist attack could help break the deadlock on the Palestine question.

The raid, engineered by Abul Abbas' terrorist group, forced a hard decision on Baker. The facts of life were laid out to him last week in secret cable from Ambassador Robert Pelletreau in Tunis, who has headed the U.S. side in talks with the PLO. He informed the secretary that Yasser Arafat lacks the power to expel Abul Abbas from the PLO's high command. By demanding that he do so, said Pelletreau, the United States would have to put a hold on the dialogue in order to preserve its credibility once Arafat said no -- however violent the repercussions in the Arab world.

Baker really was left with no choice, given U.S. and international outrage over the attempted Tel Aviv raid. He demanded action against Abul Abbas and, when Arafat was silent, decided to suspend the PLO talks (with the announcement scheduled for this week).

That suspension may well result in provoking the intifada to new fury. Yet, it may be fortuitous, giving Shamir the U.S.-PLO breakup he has called for so often. Jerusalem has sent private signals that Shamir wants to move to the peace table and rid himself of demands by hard-liners for tougher handling of the Palestinians, including deportation of troublemakers from the occupied territories.

Shamir has grown close to agreement on secret terms with Labor leaders Shimon Peres and Yitzhak Rabin for a ''unity'' government similar to the one that broke up three months ago under right-wing demands on the peace issue. The radicals demanded tougher crackdowns on the intifada, more Jewish settlements and quicker takeover of Arab land on the West Bank.

Shamir will need the votes of all such radicals in the narrow Likud government he unveiled Friday. That includes the Moledet (Homeland) Party, with a single member in the Knesset. Its party platform calls for mass expulsion of Palestinians, who total more than 1.5 million on the West Bank and Gaza.

Although Shamir has publicly accepted the support of Moledet in order to form a narrowly based government, he knows that he is playing with fire. With a Knesset majority of a single vote or two by Shamir's Likud Party, Moledet's sole member could demand a seat in the Cabinet or overthrow the government on a key issue.

American Jewish leaders say Shamir does not want to play that game for two reasons: first, he fears a major backlash from the American Jewish community and the Bush administration, which oppose the narrow coalition announced Friday; second, he really does want to lay the foundation for Palestinian autonomy, or local government, in the West Bank and Gaza. No chance for that if he has to depend on right-wing radicals.

This points to Shamir signing a ''unity'' pact with Labor, perhaps very soon. Simultaneously, Baker is counting on the suspension of the U.S.-PLO talks to bring a softer stance from Shamir on what broke up the last Israeli coalition: whether to talk to any Palestinians from East Jerusalem or with any Palestinian who has been deported from the West Bank and Gaza. Secret conversations between Shamir and Labor may have produced some solution that could be sold to the Palestinians.

But with a temporary American rebuff of the PLO, the Palestine deadlock is on the brink of its most dangerous crisis since the start of the intifada two and one-half years ago -- as Baker is all too aware. The region's climate is particularly dangerous considering Iraq's rise as the new, war-tested Arab leader against Israel and the possible overthrow of Jordan's King Hussein by Moslem fundamentalists or his kingdom's Palestinian majority.

If Shamir sticks to the narrow coalition he announced Friday, these could be curtain-raisers for much worse. In fact, there is room for some restrained hope for a more reasonable course in Israel.