A judicial overhaul has prompted many military reservists to avoid volunteer duty. Military leaders have privately warned that this might require scaling back operations.

or weeks, Prime Minister Benjamin Netanyahu has defied critics of his plan to weaken Israel’s highest court: the hundreds of thousands of people who have turned out for protests, the former prime ministers and defense officials, prominent American Jews and Israel’s attorney general.

But he may not be able to ignore a groundswell of dissent from one key Israeli institution: the powerful and influential military.

A growing number of Israeli reservists have threatened to withdraw from voluntary duty in recent weeks if the far-right government that took power late last year pushes ahead with its contentious plan to increase its control over the judiciary, the military says.

The military chief of staff, Lt. Gen. Herzi Halevi, has told government leaders that the number of reservists reporting for duty this month fell so far that the military was on the verge of reducing the scope of certain operations, according to three Israeli officials who spoke on condition of anonymity because they were not authorized to speak publicly. The officials did not provide further details

The military high command is also concerned about the possibility of resignations from full-time soldiers, two of the officials said.

Analysts say the crisis threatens to undermine Mr. Netanyahu’s reputation as a security expert who prioritizes the safety of the country above all else. Violence is surging in Israel and the occupied West Bank, and fears are growing of threats to Israel’s security from Iran and the Hezbollah militia in Lebanon. The concerns over morale in the military were at the heart of a drama on Thursday night when the defense minister, Yoav Gallant, met with Mr. Netanyahu to warn him about the effects of the turmoil within the ranks. That intervention came before Mr. Gallant was about to speak out against the judicial plan.