How US foreign policy could change

President Reagan's new foreign policy team is likely over the long run to bring change in the American approach to several key regions of the world, most notably Europe and the Middle East.

At the same time, Mr. Reagan and his advisers are moving swiftly to assure friends and allies that they will see more foreign policy continuity than change.

At a time of tension with the West Europeans over East Bloc trade and with the Arabs and Israelis over Lebanon, the administration does not want to create the impression that it is making a sharp break with the past. For one thing, uncertainty over Washington's intentions could provoke further Israeli military actions in Lebanon.

What is clear, however, is that Alexander M. Haig Jr. resigned last week in clear disagreement with President Reagan's White House advisers on several policy issues. Those White House advisers are now expected to play more of a leading role in making foreign policy.

Everyone agrees that Secretary of State-designate George P. Shultz will be more of a team player than was the headstrong Mr. Haig. William P. Clark, the president's national security adviser, is likely to continue to gain in influence with the President. And all of this is likely to mean new direction from the White House when it comes to dealing with the Soviet Union, Western Europe, the Middle East, and possibly China:

* The Soviet Union - National Security adviser Clark, Secretary of Defense Caspar W. Weinberger, and other advisers have felt for some time that by reducing the Soviet Union's access to Western trade and technology, they could intensify the Soviet Union's economic problems. They would thus hope to cause Moscow to pay more attention to its domestic problems and less to expanding its power throughout the world.

Secretary Haig felt that there were severe limits on what the US could do in this regard and that Washington would be seen by its European allies as engaging in a form of economic warfare against the Soviet Union. West Europeans tend to favor trade with the Soviets as a means of moderating Soviet behavior, helping to meet European energy needs, and offsetting West Europe's growing unemployment problem. By agreeing to cut down on subsidized credits to the Soviets, the Europeans thought they had secured agreement from the Reagan administration not to try to block the projected natural gas pipeline linking the Soviet Union and Western Europe. As Haig -- and the Europeans -- saw it, Reagan's decision to cut US technology going to the pipeline project through subsidiary companies went against this understanding. In Haig's view, the Reagan decision would have little impact on the pipeline project while causing a major rift in the Western alliance. Haig favored maintaining a dialogue with the Soviets -- and arms control negotiations with Moscow - partly as a means of countering the European and American antinuclear movements.

If it wants to reestablish close ties with Western Europe, the new foreign policy team in Washington will have to reassert its interest in such a dialogue, and in arms control negotiations. But the departure of Haig is also likely to give new confidence to those who believed the administration ought to pursue a more confrontational policy toward the Soviet Union. At the Defense Department, those who favored putting more emphasis on getting the Soviets to cut the advantage they hold in ''throw weight'' - the total potential payload of their nuclear missiles - are likely to reassert their view more forcefully. That could mean slower progress in arms control.

* Western Europe -- At the Defense Department, Haig was viewed by a number of high-ranking officials as deferring too often to the West Europeans and too much to West German Chancellor Helmut Schmidt in particular. As one of them put it, Haig's foreign policy was a ''Schmidt-oriented policy.'' But one of the ironies of the situation is that the man who has been appointed to replace Haig, George P. Shultz, has long been known as one of Schmidt's closest friends in the United States. Shultz can, therefore, play a role in reassuring the West Europeans that there will be no radical change in foreign policy following the departure of Haig. This is one reason many political ultra-conservatives are unhappy with the Shultz appointment.

White House advisers who felt that Haig was letting the Europeans off too lightly in their dealings with the Soviets, are, meanwhile, likely to have more of a say in the matter of East-West trade. Shultz has in the past opposed the use of trade sanctions, but as a team player, he may find that will have to go along with a harder line.

* The Middle East -- State Department officials say that by the time he resigned, Haig's approach to the Israeli invasion of Lebanon was being opposed by all the senior advisers at the White House as well as by Secretary of Defense Weinberger. Those advisers favored putting more pressure -- including public pressure -- on Israel's Prime Minister Menachem Begin in order to prevent an Israeli attack on the city of Beirut.

The White House used its own channels to communicate directly with Saudi Arabia's ambassador here and with the President's envoy in Lebanon, Philip Habib. This offended Haig. The White House, including most recently the President himself, began to fear that relations with moderate Arab nations were in danger of being severely damaged by the impression that the US could not, or would not, restrain Mr. Begin. Despite Haig's belief that threats against Begin would not work, a sharp message was sent by the White House to the Israelis, according to sources here.

With the one man who urged maximum restraint toward the Israelis on the way out, the stage is now set for a tougher Reagan administration policy toward Israel. As president of the Bechtel Group Inc., George P. Shultz had close ties with Saudi Arabia. In 1980 he indicated that his only disagreement with the Reagan foreign policy approach had to do with the Middle East. Mr. Shultz favored a more ''even-handed'' approach to the Arabs and Israelis. But he will still have to take his lead from a President who has always had great sympathy for Israel.

* China -- Some officials in the White House felt that Haig went too far in trying to placate Peking and that he had not taken into enough account President Reagan's long-standing sympathies for Taiwan. In refusing to sell advanced aircraft to Taiwan, the President went along with the Haig approach, which was to emphasize the importance of ties with Peking. It is now speculated that the new foreign policy team will take a cool attitude toward Peking's demands that the US agree to cut off all arms sales to Taiwan.