Why Japan is taking the lead on cooling the Iran-Iraq war

Brinkmanship now going on between Iran and Iraq has raised the anxiety level in Washington, Tokyo, Europe, and the major stock exchanges. It has also raised some misleading headlines.

And it has tended to obscure the possibility that the time may be ripe for a Japanese-Western effort to bring about at least a partial cease-fire in a war that is in many respects the biggest since World War II.

The basic elements in the Iran-Iraq strategic equation today are these:

* If Iran were to carry through on its threat to block all oil shipping from the Gulf, Iran itself would be the biggest loser. Japan would be the second biggest. Iraq would not be affected. Europe would be less affected than the Far East.

* Iraq, by threatening to attack Iran's oil-exporting facilities, is trying to force a partial truce in the three-year-old war. Baghdad wants to have at least a truce at sea - allowing both nations to resume their oil business unhindered - even if the war on land continues.

* In the long run, Iraq's oil reserves will far outlast Iran's.

* European nations - particularly France and West Germany - are more interested in expanding ties to Iraq's oil spigot. Asia's new industrial giants - South Korea, Singapore, Hong Kong, and Taiwan, as well as Japan - are increasingly dependent on Iran's oil and that of other Gulf states whose petroleum moves through the Strait of Hormuz.

* About 80 percent of oil from states abutting the Gulf is shipped out past the strait. Pipelines carry the remaining 20 percent. Of the oil passing through Hormuz in the first quarter of 1983, 90 percent turned east toward Asian industries. Just 10 percent went toward Europe and the Americas. European strategic planners worry that the trade ties thus formed will make it inevitable in the long run that they will be competing with Asia for Gulf-produced oil - and doing so at a disadvantage.

* Pipeline geography plays a major role in this Europe-Asia user split. Four pipelines feeding oil from Iraq, Saudi Arabia, and the Gulf states serve the Mediterranean.

* Under international law and maritime regulations, the Khomeini regime in Iran cannot legally stop tanker traffic through Hormuz. To do so Tehran would have to launch an overt attack on the territorial waters of Oman, through which all Hormuz traffic, outbound and inbound, moves. Or, more likely, it might send disguised irregulars from its Baluchistan shore (near Pakistan) to launch a rocket attack on some tanker or lay mines. Such action is feasible and would skyrocket insurance rates. But its illegality would give Western navies a valid reason for moving in to protect traffic.

* Japan, the outsider with most at stake, is anxiously exerting the most leverage on Iran behind the scenes. Tokyo is playing a sophisticated hand, providing technical aid and trade to both Iran and Iraq. It has quietly increased its trade with Iran in recent months and has sent in technical teams to help Iran complete industrial projects started under the Shah and aborted by the war. Included is a large petrochemical complex.

Japan's foreign minister visited Iran and Iraq this summer in a very carefully prepared trip. Japanese diplomats reportedly showed Iranian leaders computer projections which indicated Tehran would be mistaken if it thought a long war of attrition would be in its favor.

* Both Iranian and Iraqi leaders are known to be deeply irritated at the United States and the Soviet Union for what is seen by the belligerents as a ''serves you right'' attitude.

Policy in Washington since the hostage crisis has been to let Iran stew, with little attention from the US. Experts who have dealt with the Gulf area for decades believe the time may be ripe for Washington and its European and Japanese allies to make an offer to help if a partial cease-fire covering oil facilities on the Gulf is agreed to.

The carrot the West could offer is technicians to help cap war-damaged wells and clean up the Gulf.

Strategists who have studied the history of attempts to end wars generally agree that premature moves are often useless. Such behind-the-scenes attempts are seen by the warring parties as ''meddling.'' And they make the belligerents wary so that when a viable truce solution is later proposed it is sometimes shunned.

But in this major but often forgotten war there is reason to believe that some advisers to the leaders on both sides would like to find a way to resume normal trade and business in order to refuel and restock economies dangerously drained by prolonged battle.

Iraq has long been hurt by the early destruction of its tanker-loading facilities on the Gulf. But it still has pipeline access to markets. Iran depends on tanker traffic through Hormuz Strait.

According to James Critchfield, president of Tetratech International and an authority on the Gulf area, Iraq will shortly be increasing the flow in its pipeline across Turkey to the Mediterranean from 600,000 barrels per day to well over 900,000 barrels by adding compression to the line. By next April, after further modification, that figure is expected to rise to 1.4 million barrels per day.

Plans are being discussed for constructing a pipeline from Iraq to the Petroline pipeline which crosses Saudi Arabia to the port of Yanbu on the Red Sea. That pipeline has a capacity of 1.85 million barrels, according to Mr. Critchfield, and is currently running at from zero to 50 percent of capacity. From Yanbu, tankers can shunt the oil through the Suez Canal, or it can be moved to the Mediterranean via Egypt's Sumed pipeline (capacity 1.6 million barrels, to be increased to 1.9 million in the near future).

A third Iraq-to-Mediterranean pipe, crossing Syria, is closed because of Syria's support for Iran. But even without it, expanded use of the other pipes to the Mediterranean could restore a substantial amount of the 3.6 million barrels per day that Iraq exported before the war. Even if there were no war with Iran, a big drop in European demand might have cut that total anyway.

The largest conduit for oil from this vital area, the sea route through Hormuz Strait, is not as vulnerable as is often inferred from a look at charts of the great horseshoe bend between the Arabian Peninsula and the landmass of Asia.

Charles Black, a San Francisco businessman and maritime expert who spent years in the 1970s working on regularizing a new traffic scheme for Hormuz shipping, explains the realities of that naval bottleneck as follows:

Both inbound and outbound shipping sails entirely in the territorial waters of Oman - as determined by arcs extended from two little Omani islands. Thus Tehran could not legally interfere with traffic through the strait.

Iran could ban shipping from its territorial waters in the Gulf. It could thus cause a sharp alteration in shipping routes farther into the Gulf, forcing tankers to move closer to the Bahrain-Qatar coast on the southwestern shore. That would not be more than an inconvenience.

But what if Iran disregarded maritime law - not an unlikely possibility?

First there is the fact that Iran itself would be most hurt by this act. Then there is the question of how long any action against shipping would be effective.

Mr. Black speculates that if Tehran were to use disguised forces, they might set out from Gwatar or from the large base built by the Shah at Chah Bahar, near the Pakistani border, and then regroup at Jask. They could be shrugged off by Tehran as irregulars from the long-simmering Baluchi ethnic rebellion in that area. Either mines or a rocket shot at a tanker might be enough to scare Lloyd's insurers in London to raise rates to a point that would choke off shipping. Given the current world oil glut, shippers would presumably be reluctant to pay sharply higher rates.

But actual blockage of the sea lanes through Hormuz is quite unlikely, according to Mr. Black. ''The strait is 300 feet deep at the traffic separation point,'' he notes. And with three miles' width to each lane, it would be easy for captains to steer around any marked wreck.

Furthermore, Western naval action could almost certainly ensure the free flow of tanker traffic if necessary. Early in the Iran-Iraq war, Iran threatened to block the channel. Western capitals indicated they would step in militarily if that happened. The threat disappeared.