Will summer's flurry of peace proposals flower - or wilt? History shows timing crucial to success

This has been an unusually fertile week for measuring peace plans against reality. In the Iran-Iraq war, Central America, Sri Lanka, and even Vietnam, new proposals for ending hostilities are being tested. And in the field of arms control, the superpowers are trying to iron out the last wrinkles for a deal on regional-range missiles that could lead to a fall summit for Mikhail Gorbachev in the US and a possible 1988 summit for Ronald Reagan in the Soviet Union.

It is no accident that more Nobel Peace prizes are won for good works and furtherance of international law than for specific diplomatic peace designs. Of all the peace proposals to end wars, relatively few work. But any student of history (and physics) knows that wars end. Enemies relax belligerence, then trade, sometimes even become allies. Hot objects cool.

The trick, for outside peace proposers, is to know when the time is ripe for reception of their ideas by both (or all) parties to a struggle. The concept of peace imposed by great power policemen, as envisioned in 1945 by the drafters of the United Nations Charter, is now skirted around by nations that fear to set a precedent which could later be used against them or their friends.

It is in that context that the unusual great power move three weeks ago to end the Iran-Iraq war is now being tested. The US, Soviet Union, Britain, France, and China all agreed, along with other members of the UN Security Council, on a call for a cease-fire and a settlement of that long bloody war. But so far they have not been willing to put teeth into their call with strict sanctions.

In fact, despite their joint launching of the UN resolution, Moscow has agreed to trade talks and some pipeline projects with Iran; Washington has entered into naval confrontation with Iran; Paris is engaged in hot dispute with Tehran over diplomats and terrorism; and Peking is reported to have sold the Silkworm missiles which potentially threaten Western shipping in the Gulf.

Given the unanimity on paper of those great powers, both Iraq and Iran have been careful about replying to the call for negotiated peace. Iraq, which makes no secret of wanting out of the war, quickly halted its attacks on land and in the Gulf. When Iran delayed its answer and stepped up the confrontation against Kuwait and Saudi Arabia (both backers of Baghdad), Iraq returned to the attack on Iranian land targets. If no cease-fire can be arranged under the UN plan, Baghdad will doubtless decide to return to attacks on Iranian oil exports by sea.

What Iraqi strategists will do if Iran succeeds in exporting oil by pipelines outside Iraq's bombing range may become the next question. Iraq has adroitly put much of its own oil exporting out of Iranian reach by increasing pipeline capacity through Turkey and Saudi Arabia. If Iran can similarly protect major oil exports by piping through the Soviet Union and down to a port nearer its border with Pakistan, both sides could insure themselves against financial strangulation.

In short, tested against reality, the Security Council peace plan appears to need more teeth and something beyond paper unanimity if it is to throttle down this war that flickers close to many industrial nations' oil supplies. It should be remembered, also, that it is not just Japan and Western Europe's fuel supply that is jeopardized. Any substantial interruption would raise fuel prices for all.

The test which two new Central American peace plans face is different. Both the framework designed by Costa Rica's President Oscar Arias S'anchez and the alternative put forth by President Reagan try audaciously to demand internal democratic reform in Nicaragua as well as the more usual demand that states quit meddling across borders.

At the moment the Arias plan has the main track. It, somewhat modified, is endorsed by the Central American leaders, including Washington-backed President Jos'e Napole'on Duarte of El Salvador. Its reality test is becoming clear. Will the Nicaraguan Sandinista junta meet the test of allowing a free campaign, press, and elections? Will the US White House and Congress push the contras into disarming?

The Sri Lanka truce arranged with help from the Indian Prime Minister is further along than either the Arab-Persian or Central American case. Tamil rebels have been largely disarmed and territorial protection for the Tamils has been devised. But the arrangement is fragile.

At best, such longstanding ethnic collisions can be healed where good will grows and where economic, educational, and political opportunity are afforded the minority or downtrodden side. Canada's Quebecoise, Bahrain's Shiites, and native Taiwanese provide promising examples.

At worst, ancient ethnic grudges are enshrined and grind on.

The peacemaking proposal that surfaced this week between the US and Vietnam is lesser in scale, but may be no less important if successful under test. Gen. John Vessey, former chairman of the US joint chiefs of staff, came home from Hanoi to disclose a deal between the former enemies. Hanoi would speed the search for possible living Americans (POWs or others) left behind after the Vietnam War, and the US would look into ``humanitarian'' questions involving Vietnamese orphaned or crippled by the war.

This is a delicate compromise. If it works it could lead to next steps. Among those: exit for mixed-race children and relatives of Vietnamese who fled to America; eventual Vietnamese withdrawal from Cambodia; diplomatic recognition; trade. The new generation of Vietnamese leaders presumably calculates that how it deals with the first of these questions may determine whether the latter questions are reached. It is those that would eventually mean trade with prospering Asian neighbors. Eventually that could affect Hanoi's dependence on distant Moscow as protector and supplier. Earl W. Foell is the Monitor's editor in chief. Joseph C. Harsch is on vacation.