Secretary of State George P. Shultz's first personal foray into the maelstrom of Middle East politics has ended without a clear notion of whether he will achieve his major objective: withdrawal of Israeli, Syrian and Palestine Liberation Organization forces from Lebanon.

U.S. officials believe it will probably be several weeks, if not months, before Syrian President Hafez Assad decides whether to extend the cooperation that will determine the success or failure of the Israeli-Lebanese peace agreement worked out through Shultz's mediation.

Nevertheless, Shultz's 2 1/2 weeks of shuttle diplomacy affected U.S. policy in the region in several ways that may prove profoundly important.

Most immediately, the trip produced major changes in the nature and intensity of the Reagan administration's relations with Israel and Lebanon.

Moreover, as the effort to pursue the withdrawal accord continues, there could be significant shifts in the nature of U.S. dealings with Syria.

In terms of relations with Washington, the biggest immediate winner was Israel.

By bowing to Shultz's arguments and agreeing to his Lebanon withdrawal plan, the Israelis wiped away the severe tensions that had existed between Washington and Jerusalem for the last year.

Only six weeks ago, the United States and Israel appeared to be on a collision course over two issues that had the potential of tearing apart the 35-year-old fabric of their special relationship.

One involved Israeli Prime Minister Menachem Begin's dogged resistance to President Reagan's Mideast peace initiative, which he announced last Sept. 1, and which called for Israel to give its occupied Arab territories independence "in association with Jordan."

The other stemmed from Reagan's increasingly visible frustration over Israel's delay in removing its forces from Lebanon.

Both issues have been neutralized, at least for the immediate future, and, as so often in the past, the reasons are due less to Israeli flexibility than to the continuing tensions and rivalries that divide the Arab nations.

First, the Reagan initiative became bogged down in the failure of Jordan's King Hussein to win permission from the PLO to represent the Palestinians in any expanded negotiations with Israel. As long as Hussein lacks a green light from the PLO, and there is no sign that he is likely to get one, the United States will be frustrated from moving to the next stage of trying to pressure Israel into negotiations based on the Reagan plan.

Similarly, Israel's acquiescence "in principle" to pull out of Lebanon has put Begin beyond the reach of U.S. criticism on that issue. Israeli forces will be in Lebanon for some time to come, but that is because the United States agrees that Israel has a legitimate security interest in remaining there until its Syrian and PLO foes agree to a simultaneous pullout of their troops.

In addition to easing these points of friction, Shultz also came away from his visit having established a strong personal rapport with Begin and key figures in the Israeli government. He had already been on very good terms with Foreign Minister Yitzhak Shamir and Defense Minister Moshe Arens, whom the usually formal Shultz uncharacteristically calls by his nickname of "Misha," and during his time in Jerusalem Shultz established very strong rapport with Begin, whom he had never met.

It is an open secret that Reagan will soon signal the upturn in relations by releasing his hold on the scheduled 1985 delivery of U.S.-made F16 fighter-bombers to Israel. While there is always the chance of unexpected new swings in Middle East events, the outlook is for a extended period free of turbulence between the two countries.

While Begin is known to have developed strong friendship with Shultz, Lebanon's young president, Amin Gemayel, came close to turning the secretary into a father figure. In the process, Gemayel, who has staked allhis hopes for withdrawal of foreign forces on Shultz's efforts, bound the future of his embattled, fledgling government inextricably to U.S. aid and tutelage.

When Shultz made a brief farewell visit to Beirut last Sunday before leaving the region, Gemayel was clearly reluctant to let him go, U.S. officials said.

Gemayel asked plaintively whether Shultz would consider trying to mediate between the Moslem and Christian factions whose continuing civil war is a major impediment to Gemayel's chances of establishing his government's authority throughout Lebanon.

The U.S. hope is that if the occupying forces leave, Lebanon can be turned into a peaceful, American client state. But, while Gemayel is obviously eager to cooperate with that goal, many Lebanese doubt that the bitter divisions in their society can be overcome, and they warn that the United States, through its participation in the multinational force in Lebanon, could bog down in a situation not unlike that it has faced in Vietnam and El Salvador.

That view is disputed by U.S. officials who believe that the Lebanese armed forces can reassert order with only a modest amount of U.S. training and assistance. And, while the officials acknowledge that some short-term expansion of the size and role of the multinational force will be required after foreign forces leave, they discount the idea that U.S. support of Gemayel will require propping him up with a constantly expanding commitment of troops and money.

While Shultz's mission led to strengthening of ties with Israel and Lebanon, his continued pursuit of a troop withdrawal is forcing the administration to consider whether it must seek major changes in its generally chilly relations with Syria.

Outwardly, the prospects for dramatic change do not seem very good because of Syria's unrelenting hostility toward Israel, its championing of the most radical forces within the Arab world and its deepening ties with the Soviet Union, which has invested massive amounts of equipment and advisers in rebuilding Assad's armed forces.

However, a substantial number of Mideast experts believe that Assad's regime would like to be on close terms with the United States and has moved toward Moscow only because it feels that Washington has not paid due attention to Syria's interests and position in regional affairs.

That view is understood to have been urged on Shultz during his trip by Egyptian President Hosni Mubarak and Saudi Arabian King Fahd. The argument, as one U.S. official described it, was "that the way to get the Syrians to go along with a withdrawal from Lebanon is not through pressure or threats but by stroking them and showing that the United States is sensitive to their concerns."

Shultz has been wary of moving into the maneuvering between Syria and Lebanon, saying instead that the question of Syrian withdrawal is a matter for these two countries and the rest of the Arab world to resolve.

However, many administration policy planners are known to feel that sooner or later the United States will have to try to enter the process directly and seek to negotiate between Lebanon and Syria as it did with the Lebanese and Israelis.

Whether Syria would be receptive to such a U.S. role is unclear. Some officials fear that Assad's reliance on Soviet military help has grown so great that Moscow could veto any effort to bring Washington into the act. However, Mubarak and Fahd are known to have insisted to Shultz that Assad has carefully kept the Soviets from putting limits on his freedom of action.

If the administration tries taking a direct hand in Syrian-Lebanese negotiations, it undoubtedly will seek first to work through Reagan's special Middle East envoy, Philip C. Habib, who is very well known in Damascus.

But Habib was unable, on his own, to arrange a Lebanese-Israeli accord. And, while administration officials insist that the idea has not been seriously considered yet, they acknowledge that the situation might reach a point where it will be necessary for Shultz to return to the Middle East for an encore in shuttle diplomacy.