What US needs in Lebanon: military might, political flexibility

The danger of a direct US-Soviet confrontation over a Balkanized Lebanon is on the rise. Certainly, neither side is looking for a fight. The Reagan administration wants to intimidate the Syrians and their patrons from the Kremlin rather than to engage them in a major military confrontation. And the Soviet Union is not interested in a test of wills with the United States.

White House and State Department officials categorically deny any intentions to use force to throw the Syrian Army out of Lebanon. At most there is some talk about a symbolic retaliatory strike as a punishment for the massacre of American marines, and also as a reminder that nobody can push the US around with impunity.

In Moscow, the Soviet press agency Tass has issued a statement on behalf of Soviet ''leadership circles'' warning that Washington's intervention in Lebanon may have serious consequences for the US itself. Yet the statement is vague. Lost on Page 4 of Pravda, it does not specify what consequences Moscow has in mind. Nor is it even clear that these consequences will be inflicted by the USSR rather than by the struggle of what the Soviets call ''the national patriotic forces of Lebanon.''

Despite some hopeful signs from reconciliation talks in Geneva, the situation on the ground in Lebanon continues to deteriorate. And both superpowers are increasingly involved. The Reagan administration does not have a clear strategy for dealing with the militarized chaos in Lebanon. There is a definite desire to withdraw the marines before the elections. But the administration is determined to avoid defeat - the marines are expected to complete their poorly defined mission with flying colors.

That is easier said than done. Grenada notwithstanding, the Reagan administration does not have the stomach for a major operation against well-armed Syrian forces. Marine strength in Beirut is being reduced rather than beefed up. Accordingly, in order to change the balance of power in Lebanon against Damascus, Washington is appealing to Israel for assistance. But an application fee is involved. The Shamir government will not offer Reagan a helping hand without a firm US promise to oppose any significant changes in the American-sponsored Israeli-Lebanese agreement. But without such changes the Gemayel government in Beirut does not stand a chance of cutting a deal with its opponents. And the growing US partnership with Israel inevitably helps Syrian President Hafez Assad to rally Arab support. Paradoxically, the more that Washington is openly involved in an alliance with Israel, the more it pays off for Damascus to stand up to ''imperialism and zionism.''

In addition to contributing to Syrian intransigence, the American strategic arrangement with Israel would open new opportunities for Moscow to build bridges to moderate Arab states. The Soviet Union would be strongly tempted to exploit the situation and to position itself as a great-power protector of the Arab cause. Using the Israeli military machine as a substitute for US military power is an attractive but extremely dangerous shortcut. Whatever remains of American political credibility in the Arab world may be on the line.

What the US needs in Lebanon is a combination of military might and political flexibility. In trying to influence Damascus, power is indispensable but insufficient. Military muscle has to be coupled with diplomacy. The Assad regime has to be offered some incentive to achieve reconciliation with Washington and with Israel.

It was a mistake to dispatch the marines to Lebanon. It was a compounding error to allow their mission to be transformed from peacekeeping to fighting on the side of the Gemayel government. It was inexcusable to continue pretending that the marines were just peacekeepers and not take the necessary precautions to protect their lives. The brutal attack against the marines created a political climate in the US such that the Reagan administration could have increased the American military presence in Lebanon. The opportunity was missed.

There is no easy remedy to the Reagan administration's trauma in Lebanon. Moscow's distaste for confrontation should not be seen as carte blanche for the US (in alliance with Israel) to try again to defeat the last important Soviet ally in the Middle East - Syria.

To escape slipping further into a situation in which the only alternative would be a humiliating withdrawal or the risk of conflict with Syria (and 7,000 Soviet military advisers and technicians), the US should do exactly the opposite of what the Reagan administration is attempting. The President has to accept the consequences of his errors and use his mandate from the Congress to strengthen US forces in Lebanon. Simultaneously, Israel should be strongly encouraged - and if necessary pressured - to accept modifications in the May 17 accord with the Gemayel government.

Backed by improved US military muscle and the increased ability to offer political concessions, Donald Rumsfeld will be well equipped to negotiate with Syrian President Assad. But if the new US negotiator comes to Damascus as a spokesman for the American-Israeli strategic consensus, nothing but further diplomatic setbacks and military confrontations are likely to be in the cards.