Historically exempt from compulsory military service, ultra-Orthodox seminary students are being called up as Israel's war in Gaza and potential conflict with Hezbollah on the northern border saps resources and fuels resentment against those who do not have to serve.
The Israeli military said it would start issuing initial summons orders on Sunday, beginning the recruitment screening process.
A statement noted "the increased operational needs" of the army, but did not mention how many men would be drafted or when they could start serving.
In response to the announcement, demonstrators in Bnei Brak, an Orthodox majority town, blocked a highway, attacked police and called officers "Nazis", according to a police spokesperson.
The military call-up comes after Israel's top court ruled in June that exemptions to mandatory service for ultra-Orthodox men were discriminatory and ordered religious men to enlist.
Under longstanding arrangements, ultra-Orthodox Jews, who make up about 13 percent of Israel's 10 million population, have not been subject to the draft.
The lack of regulation for the exemptions has long-proved politically contentious.
Prime Minister Benjamin Netanyahu's previous coalition government collapsed in part over the issue in 2018, leading to years of political deadlock.
Ultra-Orthodox members of his current coalition have opposed moves to recruit from their community.
The high casualty figures for soldiers fighting in Gaza since the October 7 Hamas attacks, Israel's deadliest war in decades, have inflamed the issue.
At least 325 Israeli soldiers have been killed in the Gaza campaign since the start of ground operations on October 27, according to the army.
Members of the largely insular ultra-Orthodox community, where young men of recruitment age typically study in Jewish seminaries, have taken to the streets to protest recruitment, leading to clashes with police in Jerusalem.
Last week, one leading ultra-Orthodox rabbi, Dov Lando, urged Yeshiva students to ignore the summons orders, writing in the Yated Neeman daily that it was "war" against religious Jews.
While the military begins drafting ultra-Orthodox men, Israel's government is separately seeking to address manpower needs by extending compulsory service for men to 36 months, up from 32.
