Special envoy Philip Habib is returning to his Middle East peacemaking mission with a secret weapon: the incipient wrath of Ronald Reagan, aimed (but not quite ready to be fired) at what the administration perceives to be calculated stalling if not outright intransigence on the part of Menachem Begin. Skeptical outsiders insist they will have to hear it to believe it. But insiders who have heard the president holding forth on the Middle East in recent days see genuine anger welling up.

More to the point, they report that Reagan is sending Habib back to the Middle East with authority to convey a whole new sense of intensity with which his boss now approaches the impasse over Lebanon, and what it's doing to the prestige and political capital he invested in his famous "peace initiative" of last September.

The time was when the administration actively sought to disengage Lebanon from its efforts to revive the Camp David talks on "full autonomy" for the West Bank and the Gaza district as the first phase in an effort to resolve the Palestinian problem. But the administration has come finally to the conclusion that (1) this process is going to take time and (2) it won't even get started until the Israelis, the Syrians and the PLO have been persuaded to leave Lebanon.

So a two-track approach has evolved. In next week's meeting between Jordan's King Hussein and Reagan here, continued efforts will be made to lure Hussein into the active participation in Camp David that was always contemplated for Jordan under the agreement. But nobody expects Hussein to join Israel at the bargaining table while the Israelis occupy a large slice of Lebanon; the Egyptians have made clear they would not do so either. So Lebanon becomes the fast track. And Habib's mission is to force the pace in a way designed to identify which party is most clearly responsible for obstructing progress. For now, the administration is prepared to concede that both the Lebanese and the Syrians could be more forthcoming. The Egyptians are faulted for drawing back too sharply from the spirit, if not the terms, of their peace treaty with Israel.

But the finger points increasingly at Israel in general, and in particular at the introduction of what is seen as a mischievous condition that Jerusalem be the site for at least some of the negotiations with Lebanon. This implicit "recognition" of Jerusalem as Israel's capital would be politically intolerable for Lebanese President Amin Gemayel. Hence Habib's initial proposal that at least the first round of negotiations between Lebanon and Israel be conducted entirely through an American diplomatic shuttle. And if that doesn't work? "We will have ourselves a real donnybrook with the Israelis -- if it is the Israelis that are the reluctant dragons," says a policy-maker in a position to know.

What isn't intended is any overt threat to cut off U.S. aid. Rather, the intention is to borrow from what the Reagan people have been told by Camp David participants of Jimmy Carter's handling of a critical showdown with Begin. The prospect held out by Carter, in a way that apparently did bring results, was nothing that could be considered a direct threat to Israel's security. Instead, the way the Reagan people understand it, Carter simply made it clear to Begin that their personal relationship, and by extension U.S.-Israeli relations, had turned seriously sour -- or were about to do so -- as a consequence of demonstrable Israeli intransigence.

Now that may not sound like a big deal, given Begin's record of ignoring Ronald Reagan's policy on settlements and rejecting outright a "Reagan" peace plan which in no fundamental sense departs from the Camp David accords. But that is the point: Reagan clearly hasn't conveyed his displeasure in a way that impresses Begin. Doing just that will be an important part of Habib's mission -- and of his diplomatic arsenal.