In a matter of a few days, the Reagan administration has strengthened its ties with both Israel and Lebanon. But the United States appears no closer to a withdrawal of foreign forces from Lebanon.
The administration's hope apparently is that, barring any movement on the troop-withdrawal issue, the newly strengthened US-Israeli relationship will have the effect of deterring Syria or causing it to act more cautiously in Lebanon.
As Secretary of State George P. Shultz explained it in answer to a question on Thursday, the US would like Syria's President Hafez Assad to get the following message: ''That the relationship of Israel and the United States is a strong one. That Israel will continue to be able to look to its security. And that if he feels that a military victory over Israel is the way for him to get his way, he's going to be proven wrong.''
In the view of some US officials, Mr. Assad at one point not long ago thought in terms of completely dominating Lebanon. But, in their view, a newly reactivated Israeli interest in Lebanon - including some retaliatory air strikes - has caused the Syrian leader to be more prudent.
In a breakfast meeting with reporters, Secretary Shultz indicated that the US did have some ideas about concrete steps to further a withdrawal of both Syrian and Israeli forces from Lebanon, but he would not disclose them.
There are some hints from diplomats here that the Israelis may be considering another partial withdrawal in Lebanon. If coordinated with the Lebanese government, this might advance the process of getting both the Syrians and Israelis completely out of Lebanon.
Mr. Shultz spoke shortly before meeting with Lebanon's President Amin Gemayel. Mr. Gemayel later went to the White House for a meeting with President Reagan. Afterwards, Reagan said the US will ''stand by'' the May 17 Israel-Lebanon agreement on the withdrawal of Israeli forces from Lebanon.
In his talk with reporters, Shultz said that the current ''very tense situation in the Middle East'' has been brought about ''in considerable part by the large buildup of Soviet arms and troop presence in Syria.''
''Nobody wants to go to war with anyone,'' he said. ''What we seek, obviously , is peace and stability. I think the lesson is pretty clear that you get peace and stability out of having strength and a deterrent capacity which convinces people that they are better off seeking peaceful solutions rather than they are in seeking military solutions.
''I have heard Mr. Assad give his opening statements . . . that suggest his view that, No. 1, Lebanon is part of Syria and, No. two, that he doesn't really want to talk to Israel until he's looking down their throat,'' said Shultz. ''I don't think, however, that the net of the discussion in the Arab world indicates that Mr. Assad in the end asserts a Syrian right to acquire Lebanon.
''In fact, the last time I talked with him he was very clear and we agreed to state it publicly, that Syria favors an independent, sovereign Lebanon with a strong central government. . . . That's what we think ought to happen, too. The problem is how to do it.''
On the subject of two other issues of tension in the world - strained US-Soviet relations and conflict in Central America - Secretary Shultz made these points:
* It would be difficult for the US to certify at this point that the government of El Salvador is making progress in curbing human rights abuses. Shultz said that if the Salvadorean government cannot cope with right-wing death-squad killings, that will ''erode the support'' the government now has.
* Nicaragua, Shultz said, has been making statements recently that sound ''positive,'' but there is still some question about ''the reality behind the words.'' He said that the Sandinista-led Nicaraguan government was ''not an attractive regime'' to the US or to Nicaragua's neighbors. He suggested that Nicaragua's interior minister, Tomas Borge, was being denied a visa to the United States because it had been Mr. Borge's intention to come to the US to ''propagandize.''
* Shultz will consider going to a conference on disarmament in Europe starting Jan. 17 in Stockholm. This might give Shultz an opportunity to meet with Soviet Foreign Minister Andrei A. Gromyko for the first time since the two met in Madrid in September. That meeting was taken up almost entirely with the Soviet's shooting down Korean Air Lines Flight 7. West European allies of the US are interested in increasing contacts with the Soviets in this period of tension over the deployment of new US missiles in Europe.