A good many senators and congressmen would like now to have the United States pull the Marines out of Lebanon and bring them home. Others would like to have them authorized to extend their defense perimeter to be better able to protect their main positions in Lebanon.
If you think carefully about these two theoretical options, you will come to the conclusion that neither is realistic nor practical.
To pull the Marines out entirely would be to hand over to Syria effective control of all of Lebanon not included in Israel's military frontier. It would mean abandoning an American role in the search for a long-term settlement in Lebanon. It would also mean the US Marines retreating under fire, which US marines are taught not to do.
But to send marines in deeper would mean having to send in reinforcements, a longer perimeter to defend, and more chances for snipers to fire at more marines.
Henry Kissinger says that the present situation is sterile and should not be allowed to continue.
That is correct, as far as it goes; although stopping at that point is not helpful. To be helpful, Dr. Kissinger would have had to go further and say something that would not have made him popular at the White House.
The essential fact in the Lebanon situation is that White House diplomacy made a mistake last spring, which has led like the plot in a classic Greek tragedy down to the bombings of last Sunday.
The mistake was to think that Lebanon could be stabilized without the Syrians in on the preliminary negotiations and the final arrangements.
US diplomacy presided over a round of negotiations between the Gemayel government in Lebanon and Israel and then expected Syria to agree to the terms and agree also to a withdrawal of all of its armed forces from Lebanon.
The mere fact that the agreement was made with Israel and was acceptable to Israel was enough in itself to condemn it in Syrian eyes. The fact that it conferred advantages on Israel which Israel had not possessed before Israel's invasion of Lebanon clinched the matter. Syria could not with self-respect or regard for its own interests agree to an arrangement which would give Israel a benefit from its act of invasion and no compensating advantage to Syria.
Besides, Syria is as interested in what happens in Lebanon as is Israel, or anyone else. Historically, Lebanon has been part of the Syrian empire. Beirut is the main seaport for Damascus. Syria cannot afford to allow Lebanon to fall into unfriendly hands. And Syria has just been resupplied with recent Soviet model weapons, manned by Soviet soldiers, to make up for the older model weapons destroyed by Israel during the 1982 fighting.
In other words, Syria has vital interests in what happens in Lebanon, and the power to sustain its interests.
All of this was simply ignored when Washington arranged the negotiations between the Gemayel regime and Israel without Syria. It was inevitable from the time the Gemayel-Israel agreement was announced on May 4 that Syria would reject it, which it did at once, on the valid ground that under the agreement Israel ''achieved military and political goals that it failed to achieve through its invasion of Lebanon.''
The story in Lebanon ever since has simply proved that there is no such thing as a stable and lasting arrangement in and for Lebanon without Syrian agreement. Syria holds a veto power and, obviously, Syria will exercise that veto power over any arrangement which is not satisfactory to Syria.
Syria has been exercising that veto power ever since by sustaining the militia forces of those political elements in Lebanon which oppose the Gemayel regime and oppose the arrangement that regime agreed, under US pressure, to make with Israel. The Marines have been caught in the cross fire of the fighting which has gone on sporadically ever since between the pro- and anti-Gemayel political elements in Lebanon.
The only way to extricate the Marines from this situation without either an ignominious retreat or a militarily unsound advance is by starting all over again and including Syria in the negotiations and arrangements.
The objective now, as it was last spring, is a stable, independent Lebanon at peace with both Israel and Syria. If that could be achieved, the Marines could leave with honor, with the US still an important factor in the Middle East.
But to get to the objective American diplomacy will have to do what it thought it could avoid doing last spring - talk to the Syrians first.