Television nightly provides instruction in the use of standard Iranian Army small arms, Ayatollah Ruhollah Khomeini calls for an "army of 20 million." Air raid procedures are explained to the population.

Despite such precautions, however, Khomeini probably is not wrong in asserting that in case of any military showdown with the United States, Iran's main line of defense should be its trust in God and mass uprisings.

Although much improved from its total disarray after the February revolution that swept Khomeini to power, the Iranian military is still but a shadow of its former glory as the second mightiest in the Middle East, after Israel's.

The equipment is still there: nearly 2,000 American - and British - built tanks, more than 400 U.S.-supplied combat aircraft including F4 Phantoms and sophisticated F14 Tomcats, a Navy boasting missle boats, hover-craft and destroyers.

Lacking are the spare parts, logistical know-how, maintenance and skilled -- often American -- manpower needed to keep that modern material functioning as it once did.

The pinch is on now that Western Europe has tacitly joined the United States in freezing shipments of spare parts. A mitigating factor is that the Iranian armed forces are so lavishly endowed that specialists are convinced there are parts galore to be cannibalized from existing equipment.

Nevertheless, the Air Force -- once the shah's pride and joy -- has been especially hard hit by the revolution. Specialists estimate that only a tenth of Iran's approximately 650 helicopters and perhaps a fourth of its fixed-wing aircraft can be flown -- and then often without benefit of their sophisticated weapons systems.

The Navy's main serviceable equipment is missile boats, but only half the total are believed operational.

Despite Iran's present worries about defendng itself, analysts are convinced that the revolutionary authorities are torn between a need to rebuild the armed forces and a fear that the military might become too powerful.

Suspicions of the military linger because less than a year ago it was regarded as the bulwark of Shah Mohammad Reza Pahlavi's monarchy.

Indicative of the new regime's radically changed attitude toward the armed forces was the reduction by more than one-third of the previous $10 billion defense budget. In the process, military manpower has been scaled back proportionately.

Even the formation of 20,000-strong Revolutionary Guard corps, the Islamic revolutionary government's fighting army, has not allayed the clerical leadership's fears that strong military might be tempted to wrest power.

In a page copied from the Soviet Army, Iran's armed forces are now assigned mullahs down to battalion level as the Islamic revolution's equivalent of political commissars of inspectors general.

Nevertheless, for a military whose general officers were largely purged by execution and forced retirement after the revolution, the top echelons now are considered surprisingly professional.

Although screened for their Islamic credentials, the top commanders are trained career officers. Now commanding the ground forces' seven divisions, for example, are prerevolutionary colonels.

Also functioning with reasonable efficiency, according to specialists, are headquarters and staff personnel.

However, the specialists are convinced that the armed forces will need two years to recover from the revolutionary chaos -- a year to rebuild and service neglected equipment and another year to train a solid workaday military force.

Serious problems involve discipline in a society still enjoying the unwanted joys of questioning authority in all its aspects. The problem is considered particularly acute in efforts to restore the command relationship between junior officiers and enlisted men.

On the positive side, desertions, which immediately after the revolution, reduced Army barracks to so many haunted houses, are no longer a serious problem, according to analysts.

Helping to overcome it have been serious unemployment and a government decision to stop pay for deserters.

Training appears limited to individual weapons handling, with no squad, company or battalion exercises.

Although Defense Minister Mustafa Chamran intended to purge the offficer corps, he apparently has thought better of those plans.

"If parachutists landed at the airport at Abadan," site of one of the world's largest oil refineries, "the Iranians could cope," an analyst said. "But if faced with anything more ambitious such as a full-scale invasion, chances are not so good."

In the present context that kind of attack could more likely be expected from Iraq than the United States. Mindful of Iraqi backing for the local Arab population in southwestern Iran, authorities ordered antiaircraft units dug in around Abadan airport -- with their guns facing westward toward Iraq.

Some specialists believed that even the disciplined, organized Marxist guerrillas "could present the Army with problems."

So far, however, there has been no real military test for the regular Army.

Once the Army established its right to use roads in Kurdistan, it came to an accommodation with the Kurdish guerrillas.

The Army reportedly was not unhappy to see the upstart Revolutionary Guards -- who enjoy limitless funds and equipment -- get badly blooded by the Kurds.