Israel’s Supreme Court on Tuesday ruled that the military must begin drafting ultra-Orthodox Jewish men, a decision that threatened to split Prime Minister Benjamin Netanyahu’s coalition government amid the war in Gaza.

In a unanimous decision, a panel of nine judges held that there was no legal basis for the longstanding military exemption given to ultra-Orthodox religious students. Without a law distinguishing between seminarians and other men of draft age, the court ruled, the country’s mandatory draft laws must similarly apply to the ultra-Orthodox minority.

In a country where military service is compulsory for most Jewish Israelis, both men and women, the exemption for the ultra-Orthodox has long prompted resentment. But anger over the group’s special treatment has grown as the war in Gaza has stretched into its ninth month, requiring tens of thousands of reservists to serve multiple tours and costing the lives of hundreds of soldiers.

“These days, in the midst of a difficult war, the burden of that inequality is more acute than ever — and requires the advancement of a sustainable solution to this issue,” the Supreme Court said in its ruling.

The decision threatened to widen one of the most painful divisions in Israeli society, pitting secular Jews against the ultra-Orthodox, who say their religious study is as essential and protective as the military. It also exposed the fault lines in Mr. Netanyahu’s coalition, which depends on the support of two ultra-Orthodox parties that oppose their constituents’ conscription, even as other Israelis are killed and wounded in Gaza.

Israeli courts have ruled against the exemption before, including Supreme Court decisions in 1998, 2012 and 2017. The top court has repeatedly warned the government that to continue the policy, it must be written into law — though that law would be subject to constitutional challenges, as previous ones were — while also giving the government time to hammer out legislation.