The special US links with Israel highlighted this week as a way to pry Syria out of Lebanon represent a very heavy US investment for a doubtful short-term return.
The White House's urgent political concern in Lebanon is the US Marines. Those marines must be out by next summer at the latest, and the sooner the better, the administration reasons. A calamity involving US troops at any time from the GOP Dallas convention until September could put the Republican nominee - likely President Reagan - on the defensive. As late as October, the incumbent could ride it out, the White House calculates. To come up with this week's initiatives - emphasizing US-Israeli security links, and offering the Israelis a package of arms and aid incentives - US officials acknowledge they ''walked back'' from next June to decide what they must do to extricate the marines.
So narrow a motive can hardly support a comprehensive Middle East policy.
This is where the long-range risks begin. Not only are moderate Arab nations distressed at enhanced US support for Israel, but the more radical Islamic fundamentalist forces in the Middle East will find all the more cause to castigate the United States for what they see as a Judeo-Christian conspiracy against Islamic resurgence. Assassination of Egypt's President Sadat, the attack on the US Embassy in Beirut, the seizure of American hostages in Tehran - these have foreshadowed the major religious-political movement in the Middle East today.
Already, US backing for the leadership of Christian Amin Gemayel in Lebanon and for working with Israel has been depicted as a Jewish-Christian common front. Washington's latest steps can only feed the Islamic fundamentalist reaction - unless Arab leaders can see that the US is getting something concrete in exchange for its latest closeness and generosity toward Israel.
But what did the US get? Mainly a show of US-Israeli joint muscle-flexing that might or might not bluff the Syrians into withdrawal from Lebanon. Much of what was proposed as closer security ties is already standard procedure, such as sharing intelligence. A committee to consider joint maneuvers and such won't meet for two months, and by then the American bureaucracy might have scaled back its scope. US defense leaders observe that Israel is not enough of a base for a broader military effort in the Middle East. Already the Syrians faced a secure US-Israeli front. Canceling repayment terms on credits owed the US helps Mr. Shamir politically and Israel economically, but it bears little relation to Syrian-Soviet pressure in the area. The Israelis gave not an inch on West Bank settlement or the Palestinian issue, but even on Lebanon Israeli contributions remain muddy.
If the newly affirmed US-Israel pact were so great a help in strengthening Lebanon's President Gemayel, why is Mr. Gemayel so unhappy about this week's events? He wants the Israelis to pull out of Lebanon, unilaterally if need be, according to the two countries' agreement. Israel won't pull out unless Syria does too. Hence the US and Israeli muscle-flexing toward Syria. But whether Syria - Israel too, for that matter - really wants to leave Lebanon is another question. Syria must be given a say in the reconciliation government outcome, recognizing its stake in the region. Could Gemayel-led Lebanese militiamen actually govern critical strongholds without Syrian cooperation?
Eventually, another confrontation appears likely between Syria and Israel, administration and outside observers say. Neither nation wants one now. It may be more convenient for the two adversaries to maintain the division in Lebanon for the time being.
All this is to say that turning to Israel to force Syrian withdrawal may prove a chimera. Turning to Israel itself is understandable. Israel politically and culturally, and Saudi Arabia economically, are the nations closest to the US in the region.
The marines should come out quickly. They are terribly vulnerable pawns to ensure US interest in a Lebanon settlement. This is more pressure than the marines should bear. For a pluralistic democratic government to emerge in Lebanon would be a useful example in the Arab world. But is that the US goal for the region? Or is it to keep out the Soviets?
This administration, in a jam, tends to cast all conflicts into East-West terms. It has a hard time seeing a third world for what it is, with its own tensions and evolution. The critical issue today is not Lebanon, not the Palestinian question, not Soviet adventurism in the Middle East - it's the accommodation of Muslim fundamentalism. This week's Washington actions show Washington is not yet ready to set policy on that track.