Jerusalem — The surprise exodus of relatives of Soviet diplomats from Beirut is one signal. The escalating shelling between Christian and Druze suburbs of the Lebanese capital is another.
The achievement of a US-mediated draft agreement between Israel and Lebanon is likely to spark a period of high tension in the Mideast while its future hangs in the balance.
Israel and Lebanon have not yet signed the pact which calls for Israeli troop withdrawals from Lebanon. Syria, whose ultimate approval and parallel troop withdrawals from Lebanon are critical, has castigated it. So has Syria's ally, the Soviet Union.
And the United States - which engineered it - is urgently seeking the help of moderate Arab states to save it, as US Defense Secretary Caspar Weinberger meets in Paris with the Saudi defense minister.
But as these players all jockey for position, and regional tension continues to rise, each will face increasing political pressures and unanswered political questions that must be resolved before the Lebanon agreement is implemented.
In Lebanon the pullout of Soviet dependents from Beirut is a clear signal of the type of pressures President Amin Gemayel will be facing. The Soviet ambassador to Lebanon said they were leaving for summer holidays (although school is not out for another month), but Israeli Foreign Minister Yitzhak Shamir said Israel believed the Soviet aim was to press Lebanon not to sign the agreement. Israeli sources say Syrian pressure has included death threats against Lebanese leaders.
As the moment of decision draws closer, intercommunal Lebanese fighting, which has risen steadily in recent days, is bound to become more bitter, especially between the Christian militia and that of the Druze (a minority Islamic sect) in Lebanon's Shouf mountains.
Many Druze fear that if Israeli soldiers pull out of the Shouf, they will face massacres by the Christians. Pro-Syrian and pro-Palestinian Lebanese factions also want to keep Syrian and PLO troops in Lebanon to protect them, even if this means the Israelis stay, too.
The fighting has become so intense that the Lebanese parliament may be unable to meet Thursday to vote on the treaty. But the unpalatable alternative for Lebanon is de facto partition of that country between Israel and Syria - and continued bloodshed.
Israel, where officials are now expressing skepticism that the treaty will be implemented, faces domestic and external pressures in either case. Israel accepted the treaty in large part to improve relations with the United States and to shift the blame to Syria if foreign troops remain in Lebanon. But Israeli troops have suffered 482 deaths and 2,682 injuries in the Lebanon conflict to date, and many Israelis are questioning whether the sacrifice was worthwhile.
The opposition Labor Party has already decided to abstain at best on the Knesset (parliament) vote on the treaty. With several right- and left-wing Knesset members opposed, along with some members of the prime minister's Herut Party, the treaty's passage through the Knesset may be rocky.
Should Syria veto the treaty by refusing to pull back its troops, Israel would probably soon redeploy its forces along the coast and leave much of the dangerous Shouf area. That would still leave Israel heavily committed and vulnerable to guerrilla attack, in a war that is increasingly unpopular at home.
The war, along with the economy, is largely credited for the result of an opinion poll published May 6 by the daily Haaretz which for the first time in two years predicted a Labor victory over the ruling Likud coalition by a margin of 41.4 to 37.3 percent of the vote.
Moreover, Israeli Defense Minister Moshe Arens May 10 expressed concern that Syria and the PLO would take over territory relinquished by Israel, establishing a new front in a war of attrition against Israel. ''Israel would not stand for this,'' Mr. Arens said.
Such tensions could ultimately start an Israeli-Syrian flare-up. But the unpopularity of the Lebanon war would make the waging of a new war against Syria all the more difficult.
Syria has many incentives to raise tensions and draw out the drama, no matter what its ultimate goal. The Syrians oppose the agreement, which they believe will expand Israeli and US influence in the region via Lebanon at the expense of their security, while ignoring Syrian regional concerns. These include retrieval of the occupied Golan Heights and a regional peace settlement that limits Israel's borders and creates a Palestinian state.
Syrian Foreign Minister Abdel Halim Khaddam, accompanying Syrian President Hafez Assad on a critical trip to Saudi Arabia, cautioned that ''normalization of relations [between Israel and Lebanon] meant Lebanon could become the gate through which Israeli goods enter the Arab world . . . and allow Israel to establish espionage networks.
''As long as the United States is viewed as unwilling or unable to address Syria's concerns, the Syrians are likely to side with the Soviet Union. Soviet military aid offsets US aid to Israel, and the Russians are equally interested in thwarting an American Mideast triumph that gives the Soviets no role. The Syrians' major risk: They or their PLO allies could spark, perhaps inadvertently , a conflict with Israel which they would again lose.
The Soviet Union, meanwhile, seems embarked on a dangerous course of fueling Mideast tensions in hopes of increasing its prestige in the region, which was sorely damaged in the Lebanon war, while thwarting the Americans. In an unusual statement the official Soviet news agency Tass accused the US and Israel of attempting to turn Lebanon ''into a staging ground for acts of aggression against neighboring Arab states and into a stronghold of US military presence in the Middle East.
''While Soviet interests in Lebanon per se are minimal, analysts here believe Russian attention is focused on a wider stage. The Soviets, they believe, do not seek a Mideast war but want to be part of any regional Mideast peace plan. They also want to add the Mideast to the global US-Soviet agenda of issues affected by their problematic and strained relationship.
All of these unresolved issues are sure to haunt the United States in its Mideast diplomacy in the coming weeks. And these concerns seem to reduce even further the already minimal prospect that President Reagan's Mideast peace plan, thwarted by the PLO under Syrian and Soviet pressure, can be rejuvenated. They also raise questions about any alternative.
US diplomacy faces a time of testing amid the Mideast tension ahead.