Wearing a blue T-shirt with a color picture of Yasser Arafat on the front, Abed lounges on a couch in his sister's home close by the Palestinian refugee camp of Burj al Barajinah.

In another five hours, the 23-year-old college student and the 25 young Palestinian fighters under his command--most of them still in high school--will travel about half a mile farther south, to the embattled township of Hay es Sellom next to Beirut's airport. There they will relieve another group and take up a position for the next 48 hours, keeping a day-and-night vigil against an Israeli attack.

Once there, Abed and his guerrillas will run the risk of the occasional Israeli tank or artillery shell, or the sniper's bullet fired from nearby positions held by Israeli soldiers or the Phalangist Christian militias, Israel's unofficial allies. Abed shows a wound on his left shoulder, where he says a shot nicked him 10 days ago.

On the coastal road about a mile and a half to the west, across a moonscape of barren land churned up by Israeli bombardments, Hassan and Raed survey the traffic through a checkpoint at Ouzai manned by a mixed group of Palestinian and Lebanese fighters.

Despite the mixture--some of the group's members belong to formerly rival outfits--all now take orders from Abu Ammar, Hassan says, using the code name of Palestine Liberation Organization Chairman Arafat.

As he speaks, the explosion of a shell and the burst of a heavy machine gun can be heard from across the moonscape that lies just north of the airport. Five shells landed here in 15 minutes early in the morning, but nobody was hurt, Hassan says.

He adds: "The Israelis never leave people in peace."

For Abed and his fighters, and for Hassan, Raed and their men, the Israeli invason has brought not only the dangers of combat but also a good deal of uncertainty about the future, a measure of disillusionment and the possibility that an order to leave the country might not be wholly obeyed.

As a member of the PLO's mainstream Fatah guerrilla group, Abed is one of the 5,000 to 6,000 fighters Israel wants out of Lebanon. And he is certain that when this is all over, at least some Palestinians will have to leave.

He is asked what he will do if a deal is struck and Arafat orders him to leave Lebanon to go to Syria, for example.

"If he orders me to leave, yes, I will go," Abed answers. "If he orders me to go to Syria, I will go. But I will not be satisfied. I don't want to go to Syria. But I think it is possible."

At Ouzai, the southernmost point on the coastal road still held by the Palestinian and Lebanese Moslem fighters encircled in West Beirut and its southern suburbs, Hassan and Raed seem to have a different intepretation of what the current talks are all about.

"If Abu Ammar says fight, we fight," says Hassan, 28, a member of Fatah. "If he says stop, we stop." But there is no question of going to Syria.

"He doesn't say this," says Raed, 33, a member of the Palestine Liberation Army. "Abu Ammar says only we're going to Palestine or we're going to die here."

But what if ordered to go to Syria?

"We will only go to Palestine," Hassan says emphatically. "We're not going to another country."

With two more years to go to get a degree in business administration from Beirut University College, Abed faces an uncertain future even if he is able to remain here when the war is over. So much depends on what happens to Fatah and the PLO, to the organization and infrastructure they have built up here.

Abed's university tuition is paid by a Fatah scholarship. "If Fatah leaves, I can't continue my studies," he says. "The budget in my home is not too good."

Like many PLO guerrillas and officials, Abed expresses deep disillusionment over the lack of help in this war from the Arab governments and the Soviet Union. Before the Israeli invason, he says, he considered himself pro-Soviet and appreciated the Soviet Union's support of the Palestinian cause.

"The Palestinian revolution is going to be destroyed militarily," he says. "Where is the Soviet Union now? After this war I don't believe in any government, Arab or foreign. I believe in what I see."

Despite the lack of support, Abed thinks the Palestinian and Lebanese fighters can beat the Israelis--or at least cause them severe casualties--if they try to attack West Beirut.

"The Israelis' problem is not to come into Beirut," he says. "It is to stay alive in Beirut."

"The Palestinians and Lebanese can put three fighters in every building with one RPG rocket-propelled grenade launcher ," Abed says. "And from every building they can destroy one Israeli tank. If they want to try to take Beirut, I say, 'Welcome.' I don't think they can do it."

A thin, wiry young man with dark skin, a black beard and an Afro-style haircut, Abed says that his group knocked out one Israeli tank and one bulldozer with RPG's in earlier fighting near the airport. Of the 25 fighters ranging in age from 14 to 21, he says only one besides himself has been wounded so far--a 15-year-old named Rabi who was hit in the left hand by a sniper.

As Abed drags on a Marlboro, and his sister, sitting on the other side of the small living room, nurses her baby, explosions can be heard in the distance.

Although his fighters are young, Abed says they are well-disciplined. Like him, he says, many underwent guerrilla training when they were 11 or 12 years old.

One of them--Ali, 16--says he joined the group out of admiration for Abed, who, he says, is "like a brother." A short youth with the beginnings of a moustache, Ali sports an Arafat shirt like his mentor's.

According to Ali, the squad is observing orders to cease fire, despite the daily Israeli sniping. He says Phalangist militia opened fire the other day during a visit by a top PLO official, Abu Jihad, who told the group, "Don't play with them." Ali adds that Abed has told the fighters that even if they see the sniper who shot Rabi, "don't shoot; time is on our side."