"I accept command of the (Israeli military) with modesty and humility... Hamas has indeed suffered a severe blow, but it has not yet been defeated. The mission is not yet accomplished," Zamir said, amid deadlock in negotiations on next steps in a ceasefire with Hamas in Gaza.

Speaking before Zamir at the ceremony at military headquarters in Tel Aviv, Prime Minister Benjamin Netanyahu told him that Israel is "determined" to achieve victory in the multi-front war that began with Hamas's October 2023 attack.

"A very heavy responsibility rests on your shoulders, the results of the war will have significance for generations, we are determined to achieve... victory", Netanyahu said.

The prime minister and the new military chief are well acquainted, as Zamir served under him as military adviser a decade ago.

"I recommended you twice (in the past)... and now a third time. Zamir's time has come", Netanyahu said.

A former tank commander, Zamir inherited command of the Israeli military at a sensitive time in Israel's war with Hamas, with the ceasefire that took effect on January 19 hanging in the balance.

Zamir, 59, will also take over operations in the occupied West Bank, where the military has deployed tanks in recent weeks for the first time in 20 years.

Zamir replaces Lieutenant General Herzi Halevi, who resigned admitting he failed to fulfil his mandate as armed forces chief.

The military has since released the findings of an internal investigation which acknowledged its "complete failure" to prevent the October 2023 attack.