During a ceremony at the Prime Minister's residence to handover Lt Gen Gadi Eisenkot the charge of IDF, Netanyahu said the next four years would be more dangerous than the previous four, and warned against the growing threat of an Iranian "empire".
Israel "will need every tool, every man, because the Middle East around us has no mercy for the weak. Only the strong survive," said Netanyahu.
"I have no doubt that the responsibility, the determination and the experience that characterise you will serve you and us in dealing with the great challenges before us," he said.
"The people of Israel depend on you, the government of Israel depends on you and, Gadi, I depend on you," he said.
Eisenkot, 54, assumed command of the IDF replacing Benny
Gantz becoming the 21st Chief of Staff.
Accepting the charge, Eisenkot said he was being elevated at a time that was "tense and full of challenges," emphasising that "only a strong army" would be able to carry out its task of deterring and winning wars.
Eisenkot joined the IDF in 1978, serving in the Golani Brigade during the First Lebanon War.
Gantz, who resigned from service in the IDF after 38 years, said Israel "will continue to experience regional and internal tumult, but always, even in the eye of the storm, our soldiers, our forces will be the honour guard and security of the Jewish people."
Reflecting on his four-year tenure, Gantz said he "did everything, despite the difficulties" to defend Israel.
"We fortified our borders well. We trained in responses on all our borders and secured our readiness for any incident at any time," he said.
In a possible reference to strained ties with the US over the Iranian nuclear programme, Gantz said it is important that Israel maintain ties with its allies and not become isolated.
The two allies have been often at loggerheads regarding possible measures to be taken against Iran to prevent it from going nuclear, with the US preferring the diplomatic track against Israel's call for severe sanctions.
Israeli leaders have described Iran's nuclear programme as an "existential threat," at times even threatening military action to foil the Islamic Republic's nuclear ambitions.
Iran has maintained its nuclear programme is meant only for peaceful purposes.

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