Ultra-Orthodox leaders are targeting a new threat to their community: the smartphone messaging service WhatsApp.

Orthodox Jews have swarmed this service ever since a 2012 anti-Internet campaign tightened communal restrictions against social networking sites like Facebook. Now, some leaders are launching a new crusade against WhatsApp, an SMS-like tool that allows users to share digital media.

“The rabbis overseeing divorces say WhatsApp is the No. 1 cause of destruction of Jewish homes and business,” read the headline of a January article in Der Blatt, the Yiddish-language newspaper published by members of the Satmar Hasidic group.

Programmers at Meshimer Filter, a Satmar-linked Web filtering firm, are seeking to block filtered phones from sharing video, photos and audio through WhatsApp, according to a member of the Satmar community who uses the filter and who spoke with employees. The firm did not respond to a request for comment from the Forward.

“It’s not under the radar anymore,” the Satmar community member said.

At a massive June 2012 rally at CitiField in Queens, ultra-Orthodox rabbis set down a firm position against unfettered Internet use. The leaders called for the use of Web filters on all computers used by Orthodox Jews, and discouraged the use of social networking and video sharing sites.

Satmar Hasidic schools now ban children whose parents have Internet access in their homes, and require that parents use Web filters on their smartphones.

Ever since the bans, followers have sought to skirt these rules, and WhatsApp has emerged as a popular dodge.

Sources were generally unwilling to be quoted by name for this story, citing both general communal aversions to appearing in the press and specific concerns about being embroiled in the coming internal debate over WhatsApp.

Hasidic Jews in Brooklyn told the Forward that the app acts as a closed social network that provides quick communication among community members with little information let in from outside. “It’s self-created media, it’s not the outside media,” said one member of the Hasidic community in the Boro Park section of Brooklyn. “[It’s] an inside ghetto media, not outside.”

WhatsApp is similar to the built-in text messaging app on a smartphone, but the messages are free and can be easily sent to large groups of friends. The group messaging function seems to drive Orthodox use of the app. Private, invitation-only groups exist among friends, relatives, neighbors and fellow yeshiva alumnae. The Boro Park Hasid said that he is in a group with family members, and that they use it to debate current events and Talmud.

Others described more mundane uses. “Saturday night, my friend sent out a message: ‘Anyone have [jumper] cables? I need a boost,’” the member of the Satmar community said. (He drove over and helped.) Two Hasidic men described friends using it to alert each other to police speed traps in Williamsburg, Brooklyn.

Use of WhatsApp spans the ultra-Orthodox gamut, from relatively liberal Boro Park to the highly strict and secluded town of New Square, in Rockland County, N.Y. Even former members of the Hasidic community use the app.

“I’m sick and tired of it a little bit,” said Lipa Schmeltzer, the Hasidic pop music star. Schmeltzer said that the number of groups he’s joined — most of them apparently music related — have become too much. “It’s not an easy task, to keep up with all these messages,” he said.

Hasidic users said that their WhatsApp groups don’t focus on national news, but do discuss local stories. The groups were exceptionally active following the disappearance of Menachem Stark, the Satmar developer kidnapped and murdered in early January. “It was very popular during the whole Stark story,” said Joseph Oppenheim, a member of the Satmar Hasidic community and the owner of the iShop, a computer store and Internet cafe in Williamsburg. “You couldn’t get it on the radio and stuff, so this was the main source [where] people got the news.”

The software is free for the first year, then continued usage costs $1. The app claimed 400 million total monthly users as of December 2013. It’s slightly less popular in the United States than its competitor Facebook Messenger, but is widely used outside the United States, particularly in Africa and South America.

Some traced the app’s popularity within the Hasidic community to the 2012 rally at CitiField. Others said use had taken off only in recent months, after usage of the formerly popular BlackBerry Messenger collapsed amid the fading popularity of BlackBerry devices.

But sources agreed that the backlash against WhatsApp started only in recent weeks.

WhatsApp had a low profile at the time of the CitiField rally. Organizers of that 2012 campaign focused their opposition on more prominent sites, like Facebook and YouTube. Now, that’s changing.

“I know that the askanim [local organizers] are very concerned about this,” Oppenheim said.

“It’s not something they can control,” said one member of the Hasidic community who lives in Williamsburg. “Anything they can’t be in control of makes them nervous.”

The Hasidic community member from Boro Park downplayed the seriousness of the Der Blatt article, which condemned WhatsApp for distracting parents from their children and for spreading gossip. The article also suggested that Hasidic people were using the app to distribute explicit photos.

“This [article] is their way of saying WhatsApp is very in,” said this source, who argued that the report should not be taken literally.

Der Blatt is, in fact, known for its exaggerated tone. But Oppenheim said that the article was in earnest. Moreover, he said, the paper is powerful enough within the community to change communal standards by taking a stand against the app.

What’s more, Satmar spiritual leader Rebbe Zalman Leib Teitelbaum said in a speech in December that belonging to WhatsApp groups destroys one’s “Jewish spirit,” according to a report in Yeshiva World News.

Some were critical of the potential ban. Schmeltzer said that banning WhatsApp is part of a losing strategy. “It’s like banning a shopping center and then feeling the need to ban particularly aisle nine,” he said. “We’re in the shopping center, we see it didn’t work, but at least in aisle nine….”

In fact, it’s not clear how closely any of the Hasidic community’s Internet bans are followed, even by apparently pious community members.

The Williamsburg Hasidic community member said that some Hasidic men have started carrying two cell phones since the anti-Internet rally at CitiField in 2012: one filtered phone to show to administrators at the Satmar schools, who require that phones be filtered, and another without a filter. Another Hasidic man, the member of the Satmar community, said that he has a flip phone with no data capabilities to show in public plus an unfiltered smartphone.

Both of these men said that they had Internet-enabled computers in their homes despite communal bans. The Satmar man said that at home in front of his children he referred to his home computer as a “Mac” rather than as a “computer” so that it wouldn’t cause a problem if the children discuss it at school. The teachers at the Satmar school, he said, are the most sheltered adults in the community.

“Nobody in the school system knows what a Mac is,” he said. “They’ll ask my child if their father has a computer at home. They say no.”

Additional reporting by Frimet Goldberger.

Contact Josh Nathan-Kais at nathankazis@forward.com or on Twitter, @joshnathankazis