Did anyone say culture war? Local elections are in the offing, and what is happening in one Jerusalem neighborhood is beginning to look like a street battle - though so far, with property damage only.

Every Saturday, a group of secular residents takes to the streets of their neighborhood, Kiryat Yovel, in order to vandalize the poles and wires set up by a private Haredi (ultra-Orthodox) organization. A few days later, the Haredim fix the damage, which then recurs the following Shabbat. They claim the damage so far has cost NIS 150,000.

This set of poles and wires, known in Jewish law as an eruv, marks the boundary of the area where the ultra-Orthodox - who only just moved into the neighborhood - are permitted to carry objects outside their houses on Shabbat. There is already a municipal eruv covering the whole city, but the Haredim do not accept it. Thus in practice, this new eruv is what enables them to leave the house with their little children and strollers on Shabbat.

Both sides claim the other is taking the law into its own hands. And both complain the police are doing nothing.

"We are investigating," a police source said. "But at this stage, it is preferable to also try to calm things down. Otherwise, they will blow up in all our faces. An uncautious step on our part could bring the sides to a confrontation that would force us to deploy our forces every Saturday. The last thing we need is a new secular-Haredi front."

The eruv conflict of course has a bureaucratic side - namely, whether its construction received the proper permits or not. But it is clear to both sides what the real issue is: the demographic changes in the capital, where old-time residents are abandoning their neighborhoods and ultra-Orthodox families are moving in to take their place.

This reality is easy to see on a summer day in Kiryat Yovel's park, with its well-known "monster" slide, whose tongues used to be covered with secular children. Today, it is thronged by hundreds of Haredi children.

One of the secular activists, who was afraid to give his name, described the situation this way: "For a long time, we thought it would be possible to live with them in peace, but today, that isn't working. The easiest thing for a secular person is to leave, and thousands have already done so. We want to live here, but we can't live with them in the same neighborhood."

According to city councillor Sa'ar Netanel, who is aiding the secular residents in their fight, "the story of the eruv is only part of what is happening here. After we lost Ramat Eshkol and Ma'alot Dafna, now the battle is over the southwestern neighborhoods. The ultra-Orthodox want to take over this area."

David Eisenstein, from the organization that set up the eruv, responded: "The secular feel we are causing the area to become Haredi via the eruv. They do not understand that it is not the eruv that is bringing the Haredim, but the Haredim who are bringing the eruv. The ultra-Orthodox came here because of the low apartment prices, not the eruv. Now, it is a need that already exists. These hooligans' only intention is drive us out, to ensure that we cannot go out with our strollers."

The eruv, a symbolic boundary, defines the entire area it encloses as a private domain, in which carrying is allowed on Shabbat. A single, small fault in the system of poles, wire and supports during the Sabbath invalidates the eruv, and in practice forces families to remain at home. Even carrying keys is forbidden without the eruv, and carrying small children or pushing strollers or baby carriages is also not allowed without the eruv.

Almost every town in Israel has an eruv around it, and the local religious council is responsible for its construction and maintenance. Jerusalem also has its own eruv, but a number of smaller ones ones have been set up in recent years around certain neighborhoods. These are private initiatives by the Badatz (the ultra-Orthodox rabbinical court) and a private nonprofit group, Eruv Mehudar, which build them with money from contributions. These groups claim the municipal eruv is not strict enough and is not maintained adequately.

Almost two years ago, Eruv Mehudar started putting up dozens of poles around the southwestern neighborhoods, from Bayit Vagan through Kiryat Yovel and out to Hadassah University Hospital in Ein Karem. The organization shows anyone who asks a controversial document from the city that purports to be a permit for the eruv's construction.

But Deputy Mayor Yehoshua Pollak, who is also head of the city's planning board, told Haaretz that an eruv does not even need a permit. "I don't understand how a few poles and wires could bother anyone," said Pollak.

The municipality said it is not responsible for eruvs; that is the religious council's job.