wo visiting Western reporters were approaching the Ministry of Information here the other day in a state-owned taxi when a plainclothes security official craddling a Kalashnikov automatic rifle before the building started running toward the vehicle, waving wildly for them to go away.

After the two visitors nervously got out of the car and surrendered their passports, the jittery security official escorted them up the stairs into the new 10-story Dar el Baath building that houses the ministry.

Such seemingly unprovoked and strange behavior by a member of Syria's omnipresent security forces has become the norm in this tense capital which waits in a sense of helpless dread for the next deadly bomb to explode.

The last blast traumatized all of Damascus. A booby-trapped car parked on a busy street in Azbakyah, near the city center, exploded Nov. 29, setting a record for human destruction by a single bomb in the whole Arab Middle East. More than 200 people were killed and 400 to 500 others injured, according to unofficial Western estimates.

That bomb, the fourth in the capital since last August, has turned Damascus into a city of fear, and increased sectarian bitterness between the country's ruling Alawite religious minority and the majority Sunni population.

For 2 1/2 years now, a war of terrorism and counterterrorism has been under way between the Alawite-dominated government of President Hafez Assad and a shadowy, Moslem fundamentalist-led opposition front calling itself the Islamic Revolution in Syria. It now seems to have reached a peak of death and destruction here in the capital, a stronghold of the Sunni upper class heretofore left largely unaffected by the struggle.

This well-kept center of ancient Islamic history has become an armed camp with security forces acting as if a Trojan horse were on the loose inside. Wary plainclothes police and soldiers of the dreaded Saraya al Difa--the special Defense Brigades--wearing commando-style camouflaged uniforms , are visible on the streets all over the city.

Key government, party and military installations are lined with huge cement planters used as barriers to prevent any bomb-laden vehicle from getting too close, or its kamikaze driver from driving it up the steps and into the front door, as already happened in one previous incident.

Many streets in the capital's fashionable hillside Malki section, where embassies and ambassadorial residences intermingle with the homes of top Syrian leaders, have been closed to all traffic and placed under 24-hour guard.

One of the most heavily protected villas is the home of Rifaat Assad, brother of the president and head of the Defense Brigades. It is located next to the headquarters of the U.N. Golan Heights peace-keeping force on a six-lane highway cutting through the new suburb of Mezzeh, where the Information Ministry building is situated.

The three-lane stretch before his villa, as well as the U.N. office, has been sealed with a low wall of sand and steel antitank traps. Several machine-gun nests are installed on top of buildings overlooking it and a company of tanks has been stationed in back to help defend it.

So far there have been four incidents in front of his home, none of them apparently involving a real attack. In one, a sleepy driver failed to make the detour around the villa, crashed his truck through the sand wall and went out of control.

After firing 400 rounds into the vehicle, security men brought it to a halt, but not before killing one and possibly two of their own people in the crossfire. The driver's fate remained unclear to witnesses, but in another similar mishap involving a small Toyota pickup, the driver was shot to death after arguing with the guards.

Understandably, U.N. officials are looking for a safer building for their headquarters here.

Confined for two years largely to the northern Syrian cities of Aleppo, Homs, Latakia and particularly Hama, the war of terrorism first came to the capital in a big way last Aug. 17. On that day, a car bomb exploded outside the prime minister's office, where the Cabinet was scheduled to hold a meeting that had been fortuitously delayed.

Thereafter, one bomb went off each month until December, with targets including the Air Force building across from the American school in downtown Damascus, a building housing Soviet experts, and the fatal Azbakyah bomb apparently aimed at blowing up a nearby military police headquarters.

At first, the Assad government gave no publicity to the wave of bombings. But with the Azbakyah explosion, affecting hundreds of innocent bystanders, including many Sunnis, the government shifted tactics and used the incident in an effort to stir up public resentment against the Moslem Brotherhood.

The net effect, however, has been a kind of public paralysis, according to diplomats, plus an increase in the flight of middle-class Syrians abroad.

"People are fed up with the situation but they are powerless to do anything about it," said one diplomat. "They just see the repression getting worse and worse and they don't see any reversing of the trend. People are just leaving."

Assad has sought to assure his troubled nation that the bombings are the last acts of a defeated Moslem Brotherhood, whose members are now on the run.

"We have crushed these gangs inside the country and smashed their backbone," he said in an interview with a Kuwaiti newspaper after the Azbakyah bombing. "Some single members are in flight here and there, especially outside Syria in Arab and non-Arab countries."

The latter was a reference to Moslem Brotherhood branches in England, West Germany and the United States, which continue to be active in raising money, and possibly recruits, for their struggle inside Syria.

Diplomats and other analysts of Syrian politics are not sure that the Moslem Brotherhood alone is behind the persistent opposition to Assad's rule or the bombings. For example, some of the first explosions here were attributed initially to followers of one of Assad's chief rivals, Salah Jedid, who helped the president rise to power in the late 1960s before being pushed aside and thrown into jail by him in November 1970.

If true, it would be an interesting twist to Syria's increasingly bitter sectarian political struggle, for both Jedid and Assad are from the minority Alawite Moslem sect--a historical offshoot of the Shiite sect, widespread throughout the Middle East--albeit in different branches. The Alawites constitute about 12 percent of Syria's 11 million people and the Sunnis, 57 percent.

The bulk of evidence suggests that it is primarily the Moslem Brotherhood, exploiting Sunni resentment over increasingly oppressive Alawite rule, who are leading the opposition to Assad's rule and responsible for most of the bombings here.

Despite the mounting resentment among the Sunnis, most diplomats tend to agree with Assad's assessment that the strength of the brotherhood, inside Syria at least, is actually waning, the bombings notwithstanding.

Assad, together with his brothers and cousins, is still firmly in control, according to this and many other analysts, thanks mainly to their tight grip over the vast security apparatus extended through a network of close Alawite supporters.

In response to the threat, the regime has created more and more special security units of tried-and-true supporters. The latest of these was organized last year under Jamil Assad, another brother of the president and a Baath Party chief.

Called the Jamaiyat el Murtada (Society of the Satisfied), the organization is described by analysts as a kind of secret Alawite society. One of its first tasks has been to set up a shadowy parallel organization to the ruling Baath Party to help assure Assad's rule.

In the view of these analysts, the new group is but one more sign of the ever-growing distrust between Sunnis and Alawites, which they say is provoking moderates in both communities to support and join their respective extremists.

"In the long run, it is highly dangerous for the Alawites," remarked one. "If they lose their control, there will be a bloodbath."