Benny Gantz, a centrist member of Israel's three-man war Cabinet, announced his resignation on Sunday.
The move does not immediately pose a threat to Prime Minister Benjamin Netanyahu, who still controls a majority coalition in parliament. But the Israeli leader becomes more heavily reliant on his far-right allies.
Gantz, a popular former military chief, joined Netanyahu's government shortly after the October 7 Hamas attack in a show of unity.
His presence also boosted Israel's credibility with its international partners. Gantz has good working relations with US officials.
Gantz had previously said he would leave the government by June 8 if Netanyahu did not formulate a new plan for postwar Gaza.
