In the wake of the coordinated, well-planned savage attack mounted by the Palestinian terror group Hamas, which stunned Israel on 7 October, a seething Israeli Prime Minister Benjamin Netanyahu vowed the total annihilation of Hamas.

A "mighty vengeance" is what he promised against what he described as a "cruel enemy, worse than ISIS."

Likewise enraged by the slaughter of scores of Israelis, including over 200 revelers who were mowed down by armed paragliders and foot soldiers as they made merry at an electronic music festival outside the Re'im kibbutz, about 3.3 miles (5.3 kilometers) from the wall that separates Gaza from southern Israel, Netanyahu's words were echoed by Israeli Defense Minister Yoav Gallant who declared, "We will wipe this thing called Hamas, ISIS-Gaza off the face of the earth. It will cease to exist."

Hamas didn't spare any of the nearly 1,500 Israelis they felled —men, women, children, old people — they also took with them over 200 hostages. Within a week of the attack, Israel retaliated with an intense bombing of Central and Northern Gaza, with Israel striking over 7,000 targets, including rocket launchers, command centers, munitions factories, and leaders of Hamas. 

It has been nearly three weeks since the 7 October attack by Hamas, and it remains unclear if or when Israel will conduct a ground invasion of Gaza.

Even as Israel continues to blast enemy targets, Western leaders and the UN are pleading for a pause to give aid a chance to get through the blockade and into Gaza and for the safe release of the hostages in Hamas's hands.

On Thursday, Israel said it had briefly sent tanks into Gaza to "prepare the battlefield ahead of the next stages of combat."

Again, on Wednesday, Netanyahu vowed Israel would exact a price for the terrorist assault, which killed over 1,400.

Despite these statements by Netanyahu and the Israeli defense minister to decimate Hamas to kingdom come, there is no exact clarity as to when Israel will begin its ground invasion.

For sure, the challenges of a ground war are gargantuan. If or when such a ground invasion is finally mounted, what awaits the Israeli defense force will be sustained urban warfare in enemy territory in pursuit of an objective that, other than the total demolition of Hamas, leaves so many other vital matters hanging in the air.

The Israelites will confront at least four critical challenges in carrying out a major ground offensive.

For Council for Foreign Relations expert Max Boot, these include urban fighting, an inherently different form of warfare where buildings provide positions for defenders, and the multiplication of difficulties for Israeli combatants due to the presence of a large number of Palestinian civilians and even the hostages seized by Hamas who could be used as human shields. Then there are all the underground tunnels built by Hamas over the years, enabling them to hide from Israeli troops and emerge at unexpected moments.

There, too, is the challenge of a possible second front, with the Hezbollah in Lebanon poised on Israel's northern border. The Hezbollah has an estimated arsenal of some 150,000 missiles and rockets.

So far, Hezbollah has not mounted a major assault on Israel, but analysts fear it could do so once Israeli ground forces get into Gaza.

"A two-front conflict would be a nightmare for Israel," says Boot.

A third critical challenge consists of post-combat stabilization operations. Known in the US military as "Phase IV," this is where US efforts in both Washington and Iraq foundered badly for lack of preparation.

Israeli media have reported that the Israeli government has been struggling to develop a Phase IV plan of its own and, Boot points out, "no wonder because there are no good options."

If Israel simply attacks Hamas and then leaves — as it had done in the past — the terrorist group would just regenerate itself. If to prevent that from happening, a Palestinian Authority government would be established in place of Hamas, with help from Arab states, that could be an option.

But if that fails, Israel may have no choice but to re-occupy Gaza — a situation that could leave Israeli soldiers vulnerable to a grinding guerrilla war of the kind they faced in Lebanon in the early 1980s all through 2000.

Even as they do get into Gaza, there are many unknowns, according to Boot: how will Israel deal with the Hamas tunnel network; how skillfully will Hamas fight; will a toll on civilian lives in Gaza force Israel to suspend its offensive; will Hezbollah join the war; will this war spread across the region and draw into the fray Hamas's biggest supporter, Iran?

If Hamas is indeed physically decimated — what then should be done to stabilize Gaza after the enemy has been vanquished? Who takes over Gaza once the guns have been stilled and the smoke of war clears? What happens next?

Israel's leaders say those matters, for the moment, are not of immediate concern to them.

But at a certain point, they will become unavoidable; Israel will have to grapple with complex questions and carve out a workably resolute path through the din for its continued survival.