JERUSALEM — The detainee was the very picture of defiance.

She scrawled slogans on the walls of her cell. She mocked her interrogators by chanting loudly whenever they tried to question her, or by reviling them as traitors and stooges. She even refused to reveal her name.

Her jailers reported, however, that she also sometimes got homesick and cried. Which wasn't particularly surprising, given that she was only 12.

In recent months, Israeli teenagers and preteens have become the shock troops of a nationwide campaign of protests against Prime Minister Ariel Sharon's plan to withdraw from the Gaza Strip this summer, Israel's first such ceding of settlements in war-seized territory the Palestinians want for their future state.

Hundreds of youngsters have been arrested for offenses such as blocking highways, daubing anti-government graffiti on walls and scuffling with police and soldiers. They usually spend no more than a night or two behind bars, if that, but some have been incarcerated for weeks at a time.

The emergence of these young rebels has set off fierce debate among Israelis, encompassing questions of parental responsibility, freedom of expression, the proper use of judicial authority and the potential for what has so far been rowdy civil disobedience to boil over into real violence.

Opponents of the Gaza withdrawal tend to hold the teen lawbreakers up as heroes, likening them to the ranks of defiant young Jews who risked and, in some cases, lost their lives in Israel's fight for statehood more than half a century ago.

Others, however, see impressionable youngsters being cynically used by adults in order to promote their own political agenda — an uneasy reminder, for some, of Palestinian youngsters being exploited by militant groups like Hamas and Islamic Jihad during the past four years of fighting.

Many are the children of Jewish settlers in the West Bank, who fear the Gaza withdrawal would leave their communities vulnerable to uprooting as well.

Most are from religiously observant homes, with little or no contact with the secular world. And many strive to outdo even their settler parents in the zeal of their belief that the West Bank and Gaza are part of the Jewish people's biblical birthright.

Significant numbers of these youngsters are followers of extremist right-wing figures like the late Rabbi Meir Kahane, assassinated in 1990, who advocated the expulsion of Arabs from the West Bank and Gaza.

Many have engaged in brawls with Israeli troops trying to evacuate illegal hilltop settlement outposts scattered throughout the West Bank.

"There's no question that these kids are very motivated, very dedicated, and very focused," said Gil Kleiman, a spokesman for the Israeli national police. "They're young, but they're extremely organized and extremely savvy about their rights."

Theirs is a network at once loosely knit and tightly connected. The young activists use chat rooms, word of mouth and cellphone text messages to plan and coordinate protests.

On May 16, in what was described by organizers as a test run, anti-pullout protesters simultaneously blocked dozens of highways and roadways all over Israel, snarling evening rush-hour traffic for hours and tying up thousands of police.

Organizers bragged that the mass action proved they could effectively paralyze the country if authorities move ahead with the plan to evacuate the 21 Jewish settlements of Gaza and four smaller ones in the northern West Bank.

Authorities acknowledged the blockages were disruptive, but insisted they amounted to little more than a nuisance.

Yesterday, organizers abandoned their efforts to stage a thousands-strong protest march to the Gaza frontier after Israeli security forces blocked their way and kept them penned up at Kfar Maimon, 12 miles from the Gaza Strip.

Prime Minister Ariel Sharon has ordered the unilateral disengagement from Gaza because of the cost in blood and turmoil caused by Israel's maintenance of 8,500 Jewish settlers living among 1.4 million Palestinians.

The settlers, once a powerful political force, find themselves marginalized, said Nahum Barnea, a columnist for the Yediot Ahronot daily. "They are emotionally very, very frustrated. They don't know what to do," he told The Associated Press.

Out on the streets, the youngsters boldly defy police and soldiers. Particularly nettlesome to authorities are groups of teenage girls, clad in ground-skimming skirts, who deliberately tussle with burly officers in body armor at protests on roadways or outside the homes of government officials.

"If we get hurt, we show each other what they did to us," said Matti Ernstoff, a seasoned 16-year-old road-blocker.

Matti's mother, Sara-Rivka Ernstoff, said whenever her daughter failed to return home after a demonstration, she assumed the girl had been arrested, and also knew that Matti had probably refused to identify herself or asked to make a call home. She has never tried to dissuade her from such actions.

"Of course I worry like any mother would, but I really don't lose sleep when she's in jail," she said. "She's old enough to make her own choices."

Prosecutors have threatened, on grounds of parental neglect, to seek state custody of minors whose families knowingly leave them in jail. That has triggered heated arguments about whether such a step would ultimately be even more harmful to the child involved.

In court, many of the arrested youngsters refuse to answer judges' questions, using the stock reply of "We are Jews from the Land of Israel!" — an echo of what Jewish arrestees told captors during the British Mandate.

Girls sometimes give their name as "Sarah Aharonson," a heroine of the Jewish resistance in Palestine during Ottoman times.

Some analysts see the young activists as increasingly cut off from the mainstream of Israeli society.

"They're alienated, and I'm just not sure how they can be reintegrated," said Giora Rahav, a sociologist at Tel Aviv University with a specialty in juvenile crime. "There is a real messianism at play here, and it's very powerful as a uniting force for them, but also very isolating."

In a country in which military service is a key rite of passage, most of the young protesters do not intend to go into the army after high school, because they regard the Israel Defense Forces as the tool of a tyrannical government policy. They speak with disdain and even hatred of institutions such as the Supreme Court, the prime minister and the Knesset, blaming them for having cleared the way for the pullout.

"In many ways, they're disengaging from the state of Israel," said Mordechai Nisan, a political scientist at Hebrew University in Jerusalem.