NABATIVE, Lebanon – From the door of the shelter, the two men can see the town being blasted to bits, block by block.

Houses, streets and shops disappear. When the smoke clears, there is only another square of garbage.

Shell after shell – perhaps 100 rounds – falls closer and closer, marching slowly up the hill toward the patio of the old stone villa under which the shelter was dug.

On the patio, near the shelter stairs, Sami is edgy. He takes a few steps, stops, looks toward the center of town, picks up his machine gun and puts it down again.

Sami is young, 21, he says, and he has been fighting for only three days. He is a Lebanese from the south, a lean, black-haired farm worker who look up arms only when the Israelis invaded Lebanon last week.

From the top step of the shelter, Shehabi, the other commando at the shelter door, tells Sami to get inside and settle down.

Shehabi is in his 30s. He carries a slight paunch as comfortably as he carries his rifle. He has been through many shellings in his six years with Al Fatah. "Take it easy," he tells Sami, "there's nothing you can do."

A far-off roar announces the approach of Israeli jets.

"Mirage," someone outside yells. "Everybody in. Down."

All scramble down the rough cement steps to the blackness below, in the heart of the hill.

The planes fly so high they are difficult to see. But the commandos insist that the air crews can see them on the ground if they move around in the open. So there are orders to stay underground, around the table littered with tea glasses and orange rinds, in the dank air that stinks of kerosene.

When the bombs hit, even though they are two-thirds of a mile away, the air in the shelter vibrates with a sound too low to hear. The glasses rattle. The talk stops.

When it starts again, the subject is how long the fight will go on.

Sami and Shehabi agree. "We will fight until they are finished," Sami says. "Out of the land."

Right now, for these two, there is no fighting to be done. The bombardment and shelling of this market town have lasted most of the day. The Israeli firepower is awesome. The invaders have emptied and smashed Nabatiye, at least for the moment, without setting foot within five miles of the town.

But the commandos are still here, in shelters like these, and Shehabi, the veteran, knows it is a victory of sorts.

"Look," he says, "you see what they can do. They may take this town, but how many times?  How many soldiers do you think they will have to stay in all the towns?

"And for what?" he asks.

An artillery blast nearby fans the air of the shelter. "Look," Shehabi says, as if in rebuttal. "Here we are."

And for what?

They say in the shelters and orange groves of southern Lebanon that this will be a very long, bloody war.

Unless the Israelis withdraw, or gradually build the Lebanese Christian Phalangists into a force capable of holding the south, or adopt the U.S. plan of a neutral United Nations occupation force, Israelis will die every week.

So they say in the shelters, while the bombers hammer the earth. And sometimes, so saying, they laugh.

"Begin comes for revenge of (35) Jews in the bus and loses how many – 200,300?" a young commando on a road near Tyre says, laughing. He tells his fellows: "We will send them teachers for arithmetic."

Of course, Israel's count of her war dead last week is much lower than that of the Palestinian command. Israel's own estimate is 11.

Wahtever the number, it is well known here that the death of a single Israeli soldier is an occasion for national mourning. That is an attitude on which the Palestinians hope to capitalize.

There is also no way to be sure of the number of Palestinian commandos killed in Israel's invasion. Here, too, the claims vary widely. The latest Israeli estimate is 200. The Palestine Liberation Organization says that is too high.

The commandos have been pushed away from Israel's northern frontier. From that point of view, the Israeli attack was a total success.

But in the south, a mile or two away from the new Israeli zone, it is clear that the Fatah commando brigades have not been broken, only pushed back.

And from conversations throughout the south, it is equally clear that the only guarantee of the security Israel seeks from the raids of the Fatah commandos is the death or capture of thousands of Palestinians.

"They can push, they can occupy, maybe the whole south, maybe the whole of Lebanon," a Fatah official says. "Most of our men are under orders to fire, to hit and then to escape. Why stand to fight?  Why try to stop them?  This is not the point. Not with the weapons they have.

But nobody will give up, this is what you must understand. A battle is won or lost, but a revolution like ours goes on until victory. It will be a guerrilla war," he says.

"You have seen the orange groves in the south. There are no big highways, only little roads that go in valleys, around the hills, and the trees on both sides – you have seen it. How many RPGs (rocket propelled guns, anti-tank weapons) do you think we can put in those orange groves, you see?

"They will pay. They will pay every minute. A grenade from here, an RPG from here, a bullet from there. They will pay every minute."

Right now, it is the Palestinians and the Lebanese of the south who are paying the dearer price.

The destruction is tremendous, the disruption complete. The towns are emptied little by little, carload by carload as the shelling continues.

In the strip occupied by Israeli ground forces, six miles deep into Lebanon, the troops move in with armor, wary of the suicide squads that the Palestinians are said to have left behind.

When all is quiet, the houses still standing are searched one by one, each door kicked in, each cellar probed.

The refugees from the towns and Palestinian camps leave most of their belongings behind. They stream up the roads, in cars scraping the pavement, 10 people inside, mountains of household goods on top.

Still, after four days of fighting, the Palestinians have shown they can endure and regroup. Israeli settlements south of Lebanon have been shelled from behind the new Israeli lines. Single, furtive snipers walk in and out of the new border strip the Israelis have created.

And from the still-smoking towns, the commandos emerge, to flee, to join another band, to plan another mission.

In Nabatiye now, the bombardment has stopped, or perhaps just paused. No one is sure.

Cars race out of town at 80 miles an hour, down the narrow roads like the ones the Israelis will have to patrol.

Through town, the taxi driver dodges piles of rubble and wires that may still be live. The road is rutted, and a Jeep has piled into a Peugeot ahead.

From the back seat, Shehabi tells the driver to slow down.

"You cannot outrun an airplane." he says.

A sheep has been run over just outside the town. The taximan misses the carcass by a foot. Behind, a Fiat runs over the sheep and skids to a halt in a field.

An old woman with a huge burlap bag on her head pleads by the side of the road for a ride. The cars whip past her at panic speed.

Shehabi tells the driver to let him off at a point on the coast road.

"I will stay tonight with my friend, if he is here," he says. "Oh, yes, I'll go back. Perhaps tomorrow, perhaps after tomorrow. But we will all go back."