Washington — This week marks a fundamental reexamination of US Mideast policy. The release of a captured US Navy airman, Lt. Robert Goodman Jr., is welcomed here. President Reagan pronounced himself ''delighted,'' and said he hoped that ''the Syrian government will continue to work for peace in Lebanon.'' But the episode also is viewed with some chagrin by the Reagan administration.
Lieutenant Goodman's return to this country gives considerable publicity to Democratic presidential hopeful Jesse Jackson and his free-lance diplomacy; it raises anew - as does the Pentagon report on the bombing of Marine headquarters in Beirut - critical questions about the heavy reliance on military force to reach US goals in the region; and to the extent that it is viewed as a humanitarian if not peace-seeking gesture by Syria, the captured serviceman's release adds to congressional pressures to pull back the marines.
Tuesday saw a flurry of activity in Washington regarding the Middle East. President Reagan met with special envoy Donald Rumsfeld and with Republican congressional leaders to discuss new directions in US peacemaking efforts there. House Democratic leaders gathered to reexamine congressional support for the 18 -month time limit on marine deployment in Lebanon. The Pentagon prepared new recommendations to protect US marines in Beirut.
All of this comes as US allies in the region display the limits to their patience. Italy is reducing its contribution to the Multinational Force (MNF); France will redeploy some of its troops to the more neutral UN contingent located in safer territory south of Beirut; and Israel continues to bomb PLO targets.
And so far, the US has had little help from other quarters in its effort to provide a military presence while the Lebanese government and armed forces grow in strength. Defense Secretary Casper Weinberger said recently that more than a dozen countries had turned down US requests to join the MNF.
Yet there is the realization that simply removing the MNF would be unwise given the heavily armed and willing-to-fight factions in Lebanon, that a withdrawal could precipitate the ''complete collapse'' of which Mr. Reagan warned. The last time the marines pulled out, a massacre of hundreds of Palestinians by Phalangist forces followed quickly.
Two key Republicans - Senate Armed Services Committee chairman John Tower of Texas and committee member John Warner of Virginia - are in the Mideast this week to determine firsthand whether the US marines should remain. Efforts to protect them have led to the fortress-like situation that lessens their presence as neutral peacekeepers.
Yet the President suggested in his recent press conference that the role of the marines as part of the MNF in fact could grow beyond what was earlier envisioned. He said that even after the removal of Israeli and Syrian forces from Lebanon, MNF troops would be needed to help ''achieve some stability and maintain order. . . .''
The pulling back of French and Italian troops from positions in Beirut - adding as it does to a sense of US isolation there - indicates how difficult this extended military role could be. And it illustrates that criticism of US actions in Lebanon may extend beyond US borders.
Whether this brings a change in stated US Mideast policy is another matter. This policy was clearly outlined in the Reagan Mideast peace plan put forth 16 months ago. This plan has foundered thus far on Israeli opposition and events in Lebanon. More recently, administration officials as a first step have pressed Lebanese President Gemayel to seek an accommodation with his political opponents and the religious factions they represent.
Observers at this point expect a reemphasis here rather than any sharp departure from administration policy.
''The problem is, I'm not sure the administration is pursuing its own line as actively as it might,'' said Harold Saunders, a former US government Mideast expert now with the American Enterprise Institute. ''A redoubled effort on the political front in Lebanon . . . will be necessary if they're to cope with coming pressures to withdraw the marines.''
And this necessarily involves an accommodation with members of Congress, who are feeling increasing consitutent pressure to reduce the chances of more US casualties. ''They don't have a viable policy unless they have some sort of understanding with the Congress,'' Dr. Saunders said.
An official statement from Damascus called the release of Lieutenant Goodman ''a contribution by Syria for the creation of an atmosphere which would help the withdrawal of US forces from Lebanon.''
Speaking to reporters Tuesday, the President said Ambassador Rumsfeld's return to Lebanon this week was part of a ''renewed spirit . . . to advance the cause of peace in Lebanon.'' White House spokesman Larry Speakes, however, said the US would continue sending reconnaissance flights over Syrian positions in Lebanon ''as long as the marines are under attack.'' Such flights prompted the Syrian fire that in turn brought the air strike in which Goodman was downed.