POLITICAL murders often trigger events totally contrary to the wishes of their planners. The April 16 assassination in Tunis of PLO deputy leader Abu Jihad (Khalil al-Wazir) seems to be no exception. If intended to demoralize the Palestinians and take steam out of their uprising in the West Bank and Gaza, it has failed. Instead, it has brought a reconciliation of two of Israel's most formidable adversaries, Syrian President Hafez Al-Assad and Yasser Arafat, chairman of the Palestine Liberation Organization. This could be the start of a sea change in inter-Arab relations by shoving to center stage the two Mideast actors most neglected by Israel and the United States.
The Syrian-PLO rapprochement began at Abu Jihad's funeral here and continued with Mr. Assad's welcome of Mr. Arafat, whom Assad briefly jailed and then expelled in 1983. Both sides say hard work lies ahead to resolve huge difficulties. Between 1,000 and 2,000 Palestinians, PLO officials say, are still detained in Syrian jails.
To demonstrate that the PLO wants as much of its independence as possible restored, the de facto PLO foreign minister, Farouk Qaddoumi, remained here after Abu Jihad's funeral and Arafat's visit. With approving reports in the Syrian news media, Mr. Qaddoumi made a point of returning to and using the office he worked in before the PLO's 1983 expulsion from Damascus.
No one should underestimate the force of emotion in the Arab world. Never, since 5 million Egyptians said farewell in 1970 to the late President Gamal Abdel Nasser at his Cairo funeral, has this writer seen anything to match the fervor of the 300,000 or so Palestinians - and many Syrians - attending Abu Jihad's burial and later hailing Arafat in the Yarmouk refugee settlement.
As well as being the largest settlement of Palestinians who first fled to Syria in 1948, Yarmouk is also home for nearly 100,000 Syrian refugees. In 1967, they fled Israel's advancing armies in Syria's Golan Heights, occupied since then, and formally annexed by Israel in 1981.
President Assad has been unable to recover their Golan homes for these people. Syria feels that its dignity requires soft-pedaling public notice of their plight. But no one caught in the human sea engulfing Yarmouk's narrow streets during Arafat's post-funeral visit could doubt the moral force the Syrians, refugees in their own country, exercise along with the Palestinians.
Since Syria seems to be restoring its pre-1967 position as the PLO's main base, American policymakers ought to recall what that position was. In 1964 and '65, Hafez al-Assad was an outstanding Syrian Air Force officer, but he was not wielding political power. The brightest political star in the Arab world was Egypt's President Nasser.
To cut Nasser down to size, Army officers of Syria's ruling Baath (Arab Resurrection) Party encouraged Arafat and his aides in Al-Fatah, the PLO's predominant organization, to make Syria their main base.
Syrian military intelligence helped recruit Palestinian guerrillas, mainly in Lebanon. They trained and armed them in military camps in Syria. Fatah's first declared raid inside Israel, on New Year's Day 1965, was the beginning of numerous armed actions that Damascus Radio glorified and attributed to Fatah, helping to provoke the Israeli attack and war of June 1967.
Syria, Egypt, and Jordan all had heavy losses in that war. In 1970, after King Hussein drove the PLO out of Jordan, Lt. Gen. Hafez al-Assad became Syrian president on a platform of ending Syria's isolation and defeats and of ``coordination'' with the Palestinians. This meant putting the PLO in its place and keeping it there. That place became Lebanon.
Syria's cease-fire lines with Israel after the 1967 and 1973 wars became the most peaceful and best policed in the world. President Assad severely controlled them.
In attacks that finally led to its invasion of Lebanon in 1982, Israel freely pummeled Lebanon's Palestinians. It rarely risked touching those in Syria. That could cause a new Syrian-Israeli war. That risk arises again in studies that have begun here of whether to again make Syria the No. 1 base for PLO guerrilla activity. Doing so would again convert Syria into Israel's No. 1 target.
Since the US in 1982 brokered removal of the PLO's political headquarters to Tunis and its military command, nominally at least, to North Yemen, no Arab capital wants to welcome a unified and centralized PLO high command.
Today, most Arab states are willing to vote more financial, moral, or even military help for the PLO and for the West Bank-Gaza uprising, provided the logistical bases for that help are in someone else's country.
King Hussein of Jordan, though he prevents a return of bases to his country, would face a fight for his own and Jordan's survival if Gen. Ariel Sharon and other Israeli right-wingers ever expelled the West Bank's more than 1 million Arabs.
The plan of US Secretary of State George Shultz to trade land for peace in bilateral talks built around a ceremonial international meeting has met staggering opposition in both Israel and Arab capitals. The prospective new Syria-PLO alliance is partly a result of this failure.
The Soviet Union's need for Mideast stability grows with the ethnic and religious conflicts along its own borders with Turkey, Iran, and Afghanistan, as it prepares to pull its troops from the war in Afghanistan.
For all these reasons and more, everyone concerned - Israel's leaders, President Assad, King Hussein, Egypt's President Mubarak, the warring leaders of Iran and Iraq, and the outgoing Reagan administration - should step back and reflect. If the latest US peace plan won't work, cannot the big powers and the Mideast states concerned consult among themselves on a new one?
The prospective Syrian-PLO alliance is likely to be based on the assumption that a new war is inevitable and that the Arabs should plan for either a win or a draw that will procure them favorable terms.
The next US administration will have to seek answers. But it is not too late for the outgoing one to begin that search in earnest.
John K. Cooley, a former Monitor correspondent in the Mideast, is a London-based staff correspondent for ABC News. Among his books is ``Green March, Black September: The Story of the Palestinian Arabs.''