As the earliest stages of a massive assault on Gaza City take shape, Israel is calling up tens of thousands of reservists to take part in the impending military operation.

The takeover and occupation of the largest city in northern Gaza, which Israel’s Prime Minister Benjamin Netanyahu said was one of the last Hamas strongholds, will require the military to bring in 60,000 more reserve troops and extend the service of another 20,000.

The Israeli military is already on the outskirts of Gaza City, Israel Defence Forces (IDF) spokesman Brigadier-General Effie Defrin said on Wednesday, in what he described as the first steps of the larger operation.

When the security cabinet first approved the takeover of Gaza City, Israeli officials estimated the plan could take five months or more. But on Wednesday, Netanyahu instructed the military to shorten the timeline.

After nearly two years of war, and with no end in sight amid the next major operation, Israel’s military chief warned of the added burden on the troops, many of whom have been called up multiple times to fight in Gaza.

IDF Chief of Staff Lieutenant-General Eyal Zamir told the security cabinet earlier this month that the military faced attrition and burnout, but his concerns were dismissed as Netanyahu and his coalition partners pushed ahead with the new war plans.

A new survey from the Agam Labs at the Hebrew University of Jerusalem suggested that approximately 40 per cent of soldiers were slightly or significantly less motivated to serve, while a little more than 13 per cent were more motivated.

The findings underscore the stark reality facing Israel’s military, which could face limits to its manpower, especially as polls have repeatedly shown an overwhelming majority of the country supports an end to the war.

Military leaders have called for the government to draft ultra-Orthodox men into service to supplement the beleaguered troops. But the vast majority of the ultra-Orthodox community has refused to serve, and at their demand, the government is pushing a broad exemption to mandatory military service. That this political debate is happening in the midst of war has only stoked the anger of many of those who serve.

After the security cabinet approved the new operation, a small reservist organisation in Israel renewed calls for soldiers to decline military orders to serve.

“Your children do not know how to refuse on their own, because it is difficult. It is almost impossible,” Soldiers for Hostages said on social media earlier this month.

Other reservist organisations have not publicly advocated for open refusal, which is more likely to be a private decision not to serve.

The IDF does not publish the numbers or percentages of reservists who do not show up when called.

‘A death sentence for the hostages’

Avshalom Zohar Sal has served more than 300 days in Gaza on four different deployments. His last deployment ended only one month ago, and he is no longer willing to return to the front line, especially to an operation in Gaza City

“I’m a little in shock that we’re still talking about this war that was supposed to end a long time ago,” Zohar Sal told CNN.

He says the doubts, that began creeping in a year ago, have only grown stronger and other members of his unit have the same worries as him.

“I think this decision is a death sentence for the hostages,” he said.

“The government talked and said all the time that we’re talking about two missions for this war: to return the hostages and to defeat Hamas. Now it’s like telling us, there’s only one goal, which I believe is not achievable: to destroy Hamas. And even this won’t destroy Hamas.”

The Israeli military has a relatively small active-duty force, comprised mostly of conscripts. To continue fighting what has become the country’s longest war ever, Israel has to rely on reservists.

But it’s not clear what percentage will answer a new round of calls to serve inside Gaza once again, especially after the military chief warned the operation could endanger the soldiers and the hostages.