The Iranian military forces of Ayatollah Ruhollah Khomeini are turning the tide and are winning all the battles in the lingering war against Iraq, U.S. specialists say.

It is a development that is making many pro-western oil states in the region nervous and which could be the first sign of Iran's re-emergence as a force in the Persian Gulf region.

Although the war, which was started by Iraq in September, 1980, has long since slipped off the front pages in the West, experts here believe it has now reached an important turning point. Iran is winning on the battlefield, and this military situation could have decisive political and diplomatic repercussions throughout the region and in the West.

Many of the half dozen pro-western Persian Gulf oil states, including Saudi Arabia and Kuwait, have openly supported and bankrolled Iraq and thus have ample reason to fear a resurgent Iran and the aggressive Islamic fundamentalism that fueled the Iranian revolution.

Specialists here say there are already signs that Iran is regaining its confidence and its appetite for external adventures. They suggest that Iranians were behind an unsuccessful coup attempt in the tiny Gulf island state of Bahrain in December.

Although Iraq does not have diplomatic relations with the United States, the Baghdad government of President Saddam Hussein also has recently shown signs of loosening its ties to Moscow and wanting better relations with Washington.

While Hussein started the war seemingly confident of a quick victory over revolution-torn Iran, of capturing some disputed border areas and perhaps of even causing the overthrow of Khomeini, the Iraqi ruler, in the view of some analysts here, could find himself out of power because of the quagmire in which his forces are stuck.

The central and most puzzling factor in the battlefield situation is what specialists say is the virtually total inactivity of the Iraqi army since the initial round of victories and land-grabbing more than a year ago.

That army retains an overwhelming edge in firepower and a numerical edge in troop strength over Iranian forces. But it failed to break up several recent successful Iranian offensives and seems unlikely to break up preparations for new assaults that U.S. sources say are expected.

Furthermore, some analysts say they believe the Iraqi army is so demoralized that it can no longer strike back and take the initiative away from Iranian forces. Thus, the military situation becomes crucial in determining the possibilities for an eventual negotiated settlement and increasingly strengthens the prospect that such a settlement would be mostly on Iranian terms.

Specialist here say they believe the Iranians are now convinced they are winning and that will only increase their insistence that Iraq meet their demands for an end to the fighting. Those demands are a complete and unconditional withdrawal from Iranian territory, identification of Iraq as the aggressor by an international panel and reparations for suffering caused by the war.

A further oddity of this strange war is that Iraq also has air superiority over Iran, but neither side uses its air force much because the vital oil facilities in both countries are mutually vulnerable to air attack.

Both countries finance their armies by continuing to export oil. Iraq could probably scare away international oil tankers from Iran's key oil shipping port at Kharg Island by even an occasional air raid. But sources here say that Iraq now has three oil pipelines operating to Turkey, Syria and Lebanon and all three are also vulnerable to attack.

In the immediate aftermath of the initial push into Iran, the Iraqis adopted a cautious strategy that was viewed as appropriate at the time. It was designed to hold on to strategic territory and waterways and to keep casualties to a minimum so as to hold down popular opposition to the war. Much of Iran's military had been destroyed in the Khomeini revolution and much front-line equipment was also lost then and in the opening phases of the Iraqi attack.

But that careful strategy has evolved into lethargy while Iranian forces, led by Khomeini's aggressive revolutionary guard that previously handled only internal security, have taken the initiative.

Reports reaching here say that the Iranians--short on equipment, forced to go to the black market for some war supplies and unable to get spare parts for their British and American tanks and armored vehicles--have turned to an infantry strategy, using "human wave" attacks against the Iraqis spearheaded by the revolutionary guards.

Since last May, the Iranians have launched a series of attacks all along the frontier. But the main and most successful assaults in which considerable ground was regained and heavy casualties inflicted on the Iraqis have come in oil-rich Khuzestan Province in the south.

The most important success came in September when Iranian forces wiped out what had been an Iraqi grip around three sides of the key oil refinery town of Abadan, effectively lifting the Iraqi siege there. Late in November, Iranian troops also launched a successful major assault in the area around the border town of Bostan, driving a wedge between Iraqi forces north and south of Susangerd, which had been the scene of some of the heaviest fighting.

Later in the month, two smaller attacks were launched in the north, presumably to keep the Iraqis off balance while another larger assault is being prepared in the south, where it is easier for foot soldiers to operate and where mud often hampers Iraqi armor.

Analysts say that despite Iraqi weapons superiority, the continued willingness to let Iranian forces mass without preemptive strikes to break up those formations will probably continue to yield Iranian victories.

Specialists here also reason that part of the Iraqi army problem grows out of the large percentage of Shiite Moslem enlisted men in the ranks. Iran is predominantly a Shiite country.

In Iraq, the Shiites represent about 50 percent of the population. While the Iraqi Shiites consider themselves Arabs and do not identify with the Iranians, they are generally viewed as a disadvantaged group in contrast to the Sunni Moslems who make up much of Iraq's elite and officer corps.

Thus, some specialists here believe that the Iraqi soldiers do not feel they have much of a stake in the war and that the Iranian human wave strategy, in particular, has a demoralizing effect on them.

Specialists emphasize that the Iranians also are operating on a shoestring and speculate that there probably are debates going on between the military and the ruling clergy about what to do next. The clergy, in this speculative analysis, probably is arguing for launching the largest new assault possible in the hope that one really big victory can bring the war quickly to an end on favorable terms.

The Iranian military, in this view, is probably arguing that it is too risky to get overextended and to chance giving Iraq a defensive victory as it did in January, 1981, when Iranian forces drove too far on an offensive that also grew out of political pressure.

Rather, the military is probably arguing to continue the current strategy, which has been successful.