Washington — Even as the marines withdrew from Beirut, President Reagan was not admitting defeat. ''I don't think . . . that you can say that we have lost as yet,'' declared the President at his Wednesday night press conference, the first he has held since the American-supported Lebanese Army began to disintegrate.
According to the President, the United States was ''not bugging out,'' but simply moving the marines to ''a little more defensible position.'' Mr. Reagan said in answer to a question that ''great progress'' was made in Lebanon in the first year after the multinational peacekeeping force went to Beirut.
But the President's view is questioned by a wide range of experts, including some in the administration. They may argue over the degree to which US interests have been damaged by what they regard as persistent miscalculations by the administration's top officials and the subsequent retreat of the marines. But most seem to agree that the US has met, if not with disaster, certainly with a serious setback in Lebanon.
The experts remain divided as to whether the US should have sent the marines in the first place. Some still thinkthe original limited mission of the marines and other members of the multinational force was a legitimate one - at first trying to protect the evacuation of the fighters of the Palestinian Liberation Organization (PLO), and then trying to serve as a symbolic, stabilizing influence so that further massacres would be prevented and diplomats could negotiate a settlement.
Where most of the experts fault the administration is in underestimating Syria and in failing to pursue a more aggressive, sophisticated, and evenhanded diplomacy simultaneously with the deployment of the peacekeeping force.
Long before the marines began to withdraw, they were seen by large numbers of Lebanese Muslims as taking sides rather than playing a neutral role. In the view of the Druze and Shiite militia leaders, the Marines, as well as the US Navy, had become part of the problem rather than part of the solution.
In a press conference dominated by questions about Lebanon, Reagan was asked about the failure of American diplomacy and about reports that Secretary of State George P. Shultz was discouraged by the outcome in Lebanon. Reagan replied that Shultz had done a ''splendid job,'' that he had every confidence in him, and that he hoped Shultz did not have any thoughts about resigning.
Asked about his interview with the Wall Street Journal on Feb. 2 in which he said that if the US pulled out of Lebanon, there would be disastrous results worldwide, Reagan said that the US was not ''cutting and running,'' because the marines would be staying on ships offshore.
Reagan left open the possibility that the US would resume naval shelling to protect Americans remaining in Beirut. He also left himself the option of sending the marines back into Beirut.
It was not clear how 1,400 marines who were no longer capable of influencing the situation while on shore would better influence it while offshore.
Most observers doubted that Reagan would return the Marines to Beirut in this election year. And administration officials, including the President, seemed to be backing away from earlier statements about Lebanon's ''vital'' importance.
To list all of the goals for the Lebanon peacekeeping mission that the administration had outlined over the past year and a half would be to admit failure. According to one expert on such matters who has at times worked closely with Reagan, for the President to admit failure would ''impair his authority.''
The initial goal, when the Marines were sent to Beirut for a second time in September 1982 was to help provide a stabilizing force in the area following the massacres of Palestinians in two refugee camps by Christian militiamen.
But the administration soon began to add much more challenging goals: creation of a strong (and presumably pro-Western) central government; reconciliation among the factions; protection of northern Israel; and withdrawal of foreign troops (Syrian, Israeli, and PLO forces).
Aside from the departure of the PLO - now placed in doubt by reports of returning PLO fighters - and the protection of northern Israel, none of these goals have been achieved. Syrian and Israeli forces are for the moment digging deeper into Lebanon than ever. And it is the Israelis themselves who are seeing to the protection of northern Israel.
Added to the earlier aims was the President's stated goal of curbing Soviet influence, now apparently on the rise because of Syrian gains in Lebanon.
At his press conference, Reagan described his attempts to hear all sides of the Lebanon issues from his advisers.
But Mideast experts contend that conflicting statements from officials following the withdrawal announcement revealed indecision as to what to do next.
One former official involved in Middle East negotiations said there are signs this indecision persists. Another expert with long experience in top-level decisionmaking said that in a crisis, the President sometimes has to ''pound the table and say, 'This is the way it's going to be.' ''
He said the President did not know precisely where he was going either when entering or when leaving Lebanon and that he clearly did not pound the table.
Differences between Mr. Shultz and Defense Secretary Caspar Weinberger over Marine deployment were never resolved. It was Mr. Weinberger and military leaders who argued that the marines were placed in an impossible position.