JERUSALEM, FEB. 19 -- The Palestinian uprising in the occupied West Bank and Gaza Strip, which exploded in December, has now become a grinding war of attrition waged largely by familiar adversaries -- Israel's security apparatus and the Palestine Liberation Organization.

The waves of desperate, almost suicidal young men defying bullets with stones and bottles have given way to a more methodical effort to keep the rebellion alive through commercial strikes, demonstrations and pressure on so-called collaborators.

Even the street battles between youths and soldiers in cities and refugee camps are more premeditated, organized by local groups who sometimes parcel out assignments such as front-line fighting, stone supplying and roof-top spotting to their members.

After weeks of scrambling to catch up to a tidal wave it neither unleashed nor predicted, the PLO appears gradually to be asserting control, especially in the West Bank, where the outlawed organization's infrastructure and grass-roots support are strongest. PLO flags and slogans, shunned by many demonstrators during the early days of the violence, are now a centerpiece in most protests.

It is largely a secret war, waged more with radio broadcasts, clandestine printing presses and local underground committees than with stones. Israel, in response, also has changed its tactics, supplementing its controversial use of physical force and beatings with selective roundups of activists, preemptive curfews and all the intelligence that its vast but tattered network of spies and informers can provide.

Palestinian activists and Israeli military officials disagree on the degree of regional coordination behind the violence, which has claimed at least 54 Palestinian lives. The activists, who are associated with the PLO, contend an underground steering committee that calls itself "Unified National Leadership for the Uprising" and includes representatives of various Palestinian factions is spearheading the unrest in the West Bank and, to a lesser extent, in the Gaza Strip.

The Israelis, on the other hand, believe the uprising is still largely a local phenomenon, led by several hundred or more grass-roots activists. "I do not think many of them have influence beyond the boundaries of their own village or group," Maj. Gen. Ehud Barak, the Army's second-in-command, told a news conference earlier this week.

But both sides agree on one thing: the violence has united the Palestinian population in the occupied territories and permanently changed conditions on the ground.

"What we are confronting is a widespread violent uprising led by a nucleus of activists who enjoy the support of the masses," said Barak, the first senior Israeli official to use the word "uprising" to describe what previously had been designated merely as "disturbances."

While he said he was confident the Army could restore "relative calm," Barak warned that the new status quo "won't be similar to the situation a year ago. The whole thing is simmering under the surface . . . and there will be eruptions from time to time."

"It started with the kids in the streets, but today everybody is doing his little bit, even the merchant class," said East Jerusalem newspaper editor Hanna Siniora, a PLO supporter. "What you see today is cooperation not only between factions but between generations."

Siniora said Palestinians had learned from past experience that a formal, public steering committee would not work because the Israelis would quickly roll up its members. "We know we have to have a loose organization," he said. "This is a national movement, but in every city there is a smaller local organization. In this way we can survive. If you pick up 20 of them, 40 or 50 will replace them. And that is why the uprising is continuing."

The unrest flagged somewhat last week, dampened by a heavy downpour and by Israel's success in sabotaging PLO efforts to recruit and successfully launch a ship with Palestinian deportees to sail to Israeli shores.

But Secretary of State George P. Shultz's projected visit here next week has given the activists a new target, and Israeli authorities expect an upswing in the violence. Police Chief David Kraus has announced a large-scale police operation in Jerusalem starting Sunday to forestall a new round of confrontations.

{Palestinian youths and Israeli troops clashed Friday in the West Bank town of Nablus, but no deaths were reported. There were demonstrations in several Gaza Strip refugee camps. In Jerusalem, scores of police deployed to prevent violence after Friday prayers, but worshipers left peacefully, Reuter reported.}

The violence began in Gaza Dec. 9, but it appeared to be dying out in late December thanks to a combination of cold, rainy weather and a tough response by the Army. Then on Jan. 3, activists contend, the flame was lit anew by two Israeli actions. One was the announced plan to expel nine activists, five from the West Bank, four from Gaza. The second was the accidental shooting death of an Arab woman by a soldier in the village of Ram on the outskirts of Jerusalem.

The planned expulsions gave Palestinians both a new grievance and a sense of unity. Five of those slated to leave were PLO activists and three others were associated with fundamentalist movements. Their punishment gave the two rival groups something in common.

Similarly, the killing of the woman gave the more established Palestinians of the West Bank a new complaint. The PLO, stymied in its efforts to take command during the first weeks of the violence, found the unrest had moved to its own backyard.

"The strength of the PLO as an organization is in the West Bank, in the universities and the trade unions, not Gaza," said a PLO supporter. "In Gaza, it's very hot when it's hot and very cold when it's cold, whereas in the West Bank things are better organized. It's the local PLO that is now driving the bus."

One arena where national leadership quickly asserted itself was in the war of words. Despite a concerted effort by Shin Bet, Israel's internal security service, whose agents raided and shut down one printing press in East Jerusalem last week and seized 25,000 leaflets, the steering committee has managed to print and distribute weekly leaflets since early January.

The leaflets have called for strikes, withholding of tax payments and boycotts aimed against Palestinians identified as collaborators or as supporters of Jordan's King Hussein. Leaflet No. 7, issued a week ago, announced a "Day of Rage" on Tuesday against the Army and Jewish settlers. Heavy rains kept demonstrators indoors, but the strike by shop owners and workers who usually travel to Israel for employment was nearly total.

The leaflets create a sense of unity that is reinforced by Quds, the clandestine radio station that has been broadcasting for several hours a day in Arabic since the middle of December. Quds, the Arabic name for Jerusalem, is based in Damascus, according to the Israeli Army. The Army says the station is operated by Ahmed Jibril's Palestinian faction, considered a renegade group by Yasser Arafat's mainstream Fatah organization. But so far the broadcasts have taken pains not to appear critical of Arafat or Fatah.

Recent broadcasts supported the "Day of Rage" and offered some homemade recipes for youths fighting the Army. It instructed listeners on how to string trip wires between houses to impede soldiers, suggested they apply a mix of motor and cooking oils to slicken streets and also suggested they place metal spikes on the roads and dig large holes in the pavement to stop military vehicles.

Israel tried to jam the broadcasts last week by broadcasting its Arab service from an AM band close to Quds. But the clandestine station jumped down a few kilohertz and continued unimpeded.

While the leaflets and broadcasts provide a sense of national direction, Palestinians and Israelis agree that the main energy behind the uprising remains local activists. A prime example can be found in the clandestine organization chart at Balata, the West Bank's largest refugee camp, located next to the city of Nablus.

The core of the underground there is Shabibeh, a Palestinian youth movement closely allied with Fatah that by last November had pretty much taken control of the camp and had beaten several persons identified as Israeli informers.

The violence began in Balata during the week of Dec. 8 when border police entered the camp in an effort to regain control. They went from house to house, smashing windows and furniture and making arrests in a crackdown that later led to the transfer of a sergeant and two of his men. Three persons were killed and dozens more detained. The camp was placed under military curfew for several weeks.

But Shabibeh has survived. According to interviews with four members, it consists of a core of 150 to 200 dues-paying members, plus maybe 1,000 others who give it loose allegiance. It also collects funds from local merchants. Shabibeh calls the money "donations," the Israelis "extortion."

Shabibeh has managed to survive, these members say, because of an infusion of new members between the ages of 14 and 17 who have been inspired by the unrest to join the organization. "There have been lots of arrests, but generally they are people who have already been to prison, people the Israelis already know," said Rayed, 23, a Shabibeh leader. "But now there is growing a new generation of people not known to the Israelis."

One reason they are not known is because the elaborate informer network that Shin Bet carefully built over 20 years has been damaged in recent months. Rayed recounted what had happened to a camp mukhtar, or leader, known as a collaborator for many years.

A decision was taken to shun the man and his family -- the Israelis say he was beaten and threatened -- and when he died last September, Rayed said the youths blocked his family's attempt to bury him in the camp. Eventually, he was buried at a Nablus cemetery but his fate served as a warning to others.

The leaflets and radio broadcasts also have called for reprisals against informers and collaborators. Workers have been encouraged to boycott their jobs in Israel and employees of a pro-Jordanian newspaper in East Jerusalem were told to quit.

The Hebrew newspaper Maariv reported last week that several employees of Israel Television's Arabic-language service have received threatening letters demanding their resignations and that one had acceded. Similarly, two members of the Ramallah municipal council have resigned, reportedly under threat.

Israel has responded by seeking to locate and arrest those behind the clandestine network. In recent days, there have been dozens of arrests in the Jerusalem area of alleged activists and instigators. At the same time, the Israelis have sought to block PLO funds from entering the territories.