Israel's military is facing a challenge on the home front unrelated to traditional threats against the Jewish state: it's over facial hair, and activists say the army's future is at stake.

Bar Pinto and Gilad Levi, two red-bearded 29-year-olds, have founded "Beard Exemptions for All" ("Ptor Zakan Lekulam" in Hebrew), a campaign challenging Israeli military rules compelling all male troops to be clean-shaven.

Pinto and Levi have taken issue with a system that grants exemptions to that rule on religious grounds, while the faces of secular troops must remain smooth.

They argue this exacerbates tensions within the ranks.

"There is an obvious discrimination between religious and secular," Pinto said.

"It's not legal," Levi added.

Military duty at age 18 is mandatory in Israel, with young men compelled to serve for nearly three years and women for two.

But increasing numbers are seeking exemptions, citing psychological conditions and other factors as grounds to avoid service.

Defence Minister Benny Gantz recently said that more than half of young Israelis were not serving in the military.

Pinto and Levi told AFP that they view military service as a sacred part of Israeli citizenship, but that with the army struggling to attract young people, rigid rules governing facial hair are counterproductive.

"We want the army to focus on what really matters: investing time and resources to defend the country," not the facial hair of its soldiers, said Pinto.

Bar Pinto and Gilad Levi are campaigning for Israeli soldiers to be allowed to grow beards
Bar Pinto and Gilad Levi are campaigning for Israeli soldiers to be allowed to grow beards AFP / Emmanuel DUNAND

"Why complicate the lives of these young men who are making an effort to serve their country and give the best years of their lives?"

Beard Exemptions for All is bolstered by a nearly 4,000-member Facebook group, an online video campaign and merchandise, including t-shirts and stickers featuring the army's logo, branded with a beard.

Israeli army rules state that "all soldiers are required to shave their faces".

But Pinto and Levi charge that there is discrimination in how that rule is enforced.

Exemptions may be granted to men who adhere to Jewish religious rulings against shaving.

Others who claim that their beard forms an essential part of their identity are also entitled to an exemption, but Pinto said he had heard stories from "thousands" of secular soldiers whose request for an exemption had been denied.

A group of 17 soldiers who agree with that assertion filed a supreme court petition in January seeking to force the army to grant exemptions to anyone who makes a request.

Levi said 1,600 troops had contributed money from their own pockets to fund the legal challenge, which had so far raised 120,000 shekels ($36,000).

Facial hair, they argued, is crucial to many young Israeli men, regardless of their level of devoutness.

"Religious and secular are brothers in arms, we live together in this country," Pinto said. "Beards should not be an issue that divides us."