LOD, Israel — Years before the mixed Arab-Jewish city of Lod erupted in mob violence, a demographic shift had begun to take root: Hundreds of young Jews who support a religious, nationalist movement started to move into a mostly Arab neighborhood with the express aim of strengthening the Israeli city’s Jewish identity.
A similar change was playing out in other mixed Arab-Jewish cities inside Israel, such as nearby Ramla and Acre in the north — part of a loosely organized nationwide project known as Torah Nucleus. They say that their intention is to uplift poor and neglected areas on the margins of society, particularly in mixed cities, and to enrich Jewish life there. Its supporters have moved into dozens of Israeli cities and towns.
“Perhaps ours is a complex message,” said Avi Rokach, 43, chairman of the Torah Nucleus association in Lod. “Lod is a Jewish city. It is our agenda and our religious duty to look out for whoever lives here, be they Jewish, Muslim or Hindu.”
But in reality, the newcomers’ presence, at times, created tensions that built up for years and erupted this month amid the latest outbreak of warfare between Israelis and Palestinians. Arab and Jewish mobs attacked each other in the worst violence within Israeli cities in decades, raising fears of a civil war. For many, the intensity of the animosity came as a shock.
For decades, hard-line Israeli nationalists have sought to shift the demographics of the occupied West Bank by building Jewish settlements, undermining the prospect of a two-state solution to the long running Israeli-Palestinian conflict.
With far less attention and fanfare, the Torah Nucleus movement set out with an ideological mission to alter the balance of Israeli cities and promote its brand of Judaism inside the country.
The first families who moved into Acre and Lod 25 years ago came from West Bank settlements, and they aimed to make mixed or predominantly Arab communities more Jewish.
With West Bank settlement firmly entrenched — about 450,000 Jews now live among more than 2.6 million Palestinians — Torah Nucleus supporters see Israeli cities as a new horizon.
Most of the world considers Jewish settlements in the occupied territories a violation of international law, but this was an attempt to create change within Israel’s recognized boundaries. And many cast it as the new Zionism.
“Religious Zionism hasn’t abandoned the old mission of Judea and Samaria,” said Reut Gets, who manages the Torah Nucleus association in Acre, referring to the West Bank by its biblical names.
But the focus now was on “the new challenge” within Israel itself, she said.
Lod, a city of about 80,000 people in central Israel, is about 70 percent Jewish and 30 percent Arab. Frictions there had long been kept on a low boil.
But on May 10, Palestinian protests and an Israeli police raid at the Aqsa Mosque in Jerusalem — one of Islam’s holiest sites — spilled over into a military conflict between Israel and Hamas, the Palestinian militant group that controls the Gaza Strip.
It quickly ignited violence between mobs of Arabs and Jews in Israel’s cities, starting in Lod and rapidly spreading across the country as internal fault lines were abruptly exposed.
In Lod, hundreds of the city’s Arab citizens took to the streets, throwing stones, burning cars and setting fire to properties, venting their rage against one primary target: The mostly young, Orthodox Jewish families who had arrived in recent years, saying they wanted to lift up the working-class city and make it more Jewish.
Worst hit were the scores of families who had moved over the last decade into a hardscrabble, crime-ridden neighborhood populated mostly by Arabs. They rented or bought apartments in the dilapidated blocks lining a warren of streets near the city’s old quarter, sharing the stairwells with longtime Arab residents.
The newcomers called it coexistence. But many Palestinian citizens of Lod viewed them as invaders and called them “settlers.”
The violence soon turned lethal. Four Jews are suspected of fatally shooting an Arab resident, Musa Hassouna, and wounding three others during a riot in a nearby neighborhood. A Jewish man, Yigal Yehoshua, died after Arabs threw a heavy rock at him.
Over the past week, the clashes subsided and early Friday, a cease-fire between Israel and Hamas took hold. But the unrest in Lod nonetheless focused attention on the role of the Torah Nucleus movement.
Its representatives vehemently deny that they have any ill intent toward the Arab population, insisting that the opposite is true. Mr. Rokach, the local leader of the movement in Lod, insisted that the program’s volunteer projects, such as distributing food to the needy, benefited Jews and Arabs.
“Coexistence is not standing on the road with a placard,” he said, mocking liberal peace activists. “It is getting up and saying good morning to your Arab neighbor and lending each other milk when necessary. We are living it.”
Rami Salama, a 24-year-old Arab resident of Lod and a building contractor whose apartment complex is now about half Arab and half Torah Nucleus families, said that was not his experience. He said it hurt him that his new Jewish neighbors never answered when he bid them good morning or a happy holiday.
“They want to rule here,” he said. “I blame the Arabs who sold them the apartments,” which he added had since doubled in value. “The violence wouldn’t have happened if it wasn’t for the settlers,” he said.
The Lod neighborhood at the heart of the violence, Ramat Eshkol, was abandoned by many of its Jewish residents decades ago and there, the city’s Jewish-Arab ratio is reversed. About 70 percent of Ramat Eshkol is Arab.
Across all of Israel, there are about 70 active hubs of Torah Nucleus, supported by an umbrella organization, the Community Renewal Foundation, which gets some government funding.
Izhak Lax, the chairman of the foundation, said the idea was for young activists, many of them professionals and graduates of army combat units, to establish homes in the geographical and socioeconomically weak margins of the country and contribute to improving them.
Their presence stretches from the predominantly Jewish desert towns of Yeruham and Dimona in the south to Kiryat Shemona on Israel’s northern border with Lebanon. Of some 10,000 families involved nationally, about 1,200 of them are in Lod.
But Mr. Lax countered claims that they had come “to conquer” Lod and displace the Arabs. “Where can we settle if not in a city in the middle of Israel?” he said.
In Acre, up to 200 Torah Nucleus families have taken up residence. One member of the community was among those injured in the disturbances, a teacher in his 30s who was beaten unconscious by Arabs. Arabs also burned down Jewish-owned tourist sites.
Jewish vigilantes from across the country quickly organized on social networks and sought out Arab victims in Lod and other cities, beating an Arab man almost to death in the Tel Aviv suburb of Bat Yam.
Lod, which traces its history to the days of Canaan and is known as Lydda in Arabic, has a particularly fraught history centered around the creation of the state of Israel in 1948. Most of the original Palestinian residents of the city were expelled and never allowed to return.
Bedouins — the seminomadic Arabs from Israel’s Negev desert — arrived in the following decades as did families of Palestinians from the West Bank who had collaborated with Israel, seeking refuge.
Now, Arab rage here is steeped in a smarting sense of inequality born of decades of government neglect and discrimination.
The city’s mayor, Yair Revivo, has pressed in the past to tone down the volume on the Muslim call to prayer from minarets in the city and his right-hand man is a founder of Lod’s Torah Nucleus.
Arab resentment is compounded by a lingering fear of displacement, house by house.
About eight years ago, Torah Nucleus built a pre-army academy and a religious boys’ elementary school next to the long-established school for Arab pupils on Exodus Street in the heart of Ramat Eshkol.
These Jewish institutions were the first to be set on fire on May 10. The trouble started after evening prayers, witnesses said. Arab youths raised a Palestinian flag in the square and demonstrated in solidarity with Palestinians in Jerusalem and Gaza. The police dispersed them with tear gas and stun grenades.
Angry Arab mobs then went on a rampage, burning synagogues, Jewish apartments and cars in Ramat Eshkol. One group approached another Torah Nucleus neighborhood, where a Jewish crowd had gathered.
There, the four Jewish suspects in the shooting claimed, they fired in the air in self-defense as Arab rioters began to rush at them, throwing stones and firebombs, according to court documents.
The funeral for the victim, Mr. Hassouna, the next day devolved into new clashes as the mourners, the building contractor Mr. Salama among them, insisted on passing through Exodus Street with the body in defiance of police instructions.
That night, gangs of Jewish extremists, some of them armed, came from out of town to attack Arabs and their property, according to witnesses. Mr. Salama said he was hit by a stone while sitting in his garden. Gunshots were heard on both sides.
One Jewish apartment in Ramat Eshkol was burned to cinders after Arab intruders broke open a hole in the wall. The family had already left. A neighbor, Nadav Klinger, said the charred flat would be preserved as a museum.
Elsewhere in Lod, some veteran Jewish and Arab neighbors said their good relations remained intact and agreed that the influx of religious Jewish professionals had lifted the city up.
Ayelet-Chen Wadler, 44, a physicist who grew up in a West Bank settlement, came to Lod with her family 15 years ago to join the Torah Nucleus community.
“I was raised to try to make an impact,” she said. “Just by living here, you make a difference.”
A week after the peak in the violence, about 30 of the 40 Jewish families who had evacuated their homes in the Ramat Eshkol neighborhood had returned.
“I believe we can get back to where we were before, but it might take some time,” said Mr. Rokach, the chairman of the Torah nucleus in Lod, condemning the revenge attacks by Jews from outside.
“Nobody’s leaving. Quite the opposite. As we speak, I just got a WhatsApp message from a family looking for a home here. Nor are the Arabs leaving.”
Myra Noveck contributed reporting from Jerusalem.