THE rebel offensive, now entering its fourth week, has shaken the political and military realities of El Salvador so profoundly that the country will never return to the way things were before it began Nov. 11, analysts here say. The strongest offensive of the 10-year-old war is being compared to the 1968 Tet offensive in Vietnam. Both offensives jolted nations that had been constantly reassured by their governments that the leftist guerrillas were a spent military force. Both brought the war to major cities that had been relatively untouched by the fighting.
Among the apparent effects of the Salvador offensive:
The Faribundo Mart'i National Liberation Front (FMLN) has dramatically increased its military stature.
The Army and the government have lost credibility.
Capital residents, both wealthy and poor, say they feel vulnerable to a war that had previously affected mainly the rural areas.
Two million Salvadorans live in the capital - almost half the country's population. Before the offensive began, few had come into contact with the guerrillas.
But first the poor districts - where rebel forces counted on civilians to serve as a shield and where the Army carried out heavy bombardments - and then the capital's most exclusive districts became battlefields.
In the poor neighborhoods, some came to the aid of the rebels and some sought to flee, but the strafings and bombings left many barrios devastated.
``When you ask people what was the worst, they say the bombing,'' says an American relief worker who visited some of the hardest hit communities. ``They might not like that the guerrillas came into their neighborhoods, but they were really afraid of the Army.''
In one poor barrio in the southeastern part of the city, a woman slightly wounded by Air Force strafing says there was much sympathy for the guerrillas.
A man in the eastern suburb of Soyapango blames the guerrillas for provoking the Army. ``It's the guerrillas' fault,'' he says, looking at the destruction caused when the Air Force dropped three bombs, leaving craters 25 feet in diameter and destroying many homes on the street.
The Air Force refrained from bombing in the exclusive Escal'on district, despite two startling guerrilla incursions into the area of manicured lawns, satellite dishes, and elegant mansions.
During the first incursion, the rebels occupied part of the Sheraton Hotel. In the second, after senior United States Embassy personnel were trapped by the fighting, US dependents were evacuated from the country on chartered planes.
Wealthy Salvadorans have also begun to send family members out of the country. And a number have criticized the Army's performance.
``It was stupid. The Army pulled out the day before the attack and left seven or eight guys to guard this whole area,'' says Manuel Vides, a resident of the Escal'on district. ``The Army doesn't know what it's doing.''
Several diplomats here agree that the Army is in a defensive position, its troops stretched thin and tired. The FMLN, some diplomats say, seem to have studied urban warfare more than the Army, and have largely taken the initative. In the capital, the Salvadoran Army High Command has relied primarily on its elite battalions rather than using the mainly conscript brigades.
``I think the High Command is scared to put in conscript troops, especially when they don't have air support,'' says a West European diplomat. ``They can't afford to have an Army unit crumble.''
``Too many of [the Army conscripts] don't seem sufficiently motivated,'' he adds of the recruits.
Diplomats say that the FMLN offensive has strengthened Army hard-liners who favor a ``violent or repressive solution.''
While President Alfredo Cristiani says he is still open to peace talks with the guerrillas, he has ruled out making any concessions, saying he would only talk if they first agree to an ``ending of hostilities.''
``Cristiani can't offer concessions,'' says the diplomat. ``But the FMLN believe they've established the right to concessions through their offensive.''
Nonetheless, the rebel offensive may be slowly convincing some of the country's elite that concessions have to be made.
``A week ago the right was being very hard,'' says the diplomat. He notes, however, that ``events of the last week will make them think that they have to talk, that `We're being hurt directly, and that isn't acceptable.'''