The horror of October 7, after Hamas terrorists broke out of Gaza and engaged in a murder and kidnapping spree against hundreds of Israeli civilians, including women and children, caused Israel to immediately declare a state of war against Hamas. Israel said it would deal with Hamas once and for all. Leaders of all the western countries, including Australia, and most of the United Nations showed their shock and horror at Hamas' actions, and spoke immediately of Israel's right to defend itself. Even those who had previously expressed support for the rights of Palestinians condemned the Hamas atrocities unreservedly, and distinguished resistance and just claims from inhuman terrorism and the unprovoked murder of innocents.

The United States began diverting arms intended for Ukraine from its stockpiles for Israel. In opening responses, Israel began showering missiles on urban Gaza, claiming, however, that its missiles were targeted at known Hamas centres. The risks to civilians were collateral, it was said, because Hamas deliberately locates its centres in heavily populated areas, even hospitals.

In the immediate aftermath of the epic Hamas brutality, the moral advantage, for what that is worth, was entirely with Israel. This was much the same as in the United States after September 11, 2001. In both cases, that advantage began to slip as the victim nations launched assaults on those they blamed for the outrages, and commentators, seeking to put context into the surprise and outrage, began speaking of long-running grievances and a festering sense of oppression and abuse of power from the leaders of the countries concerned. Not that this justified war against civilian populations, of course. But those speaking of crude revenge had to appreciate the history and the build-up, and the risks of making things worse. After October 7, both friends and critics of Israel began speaking worriedly about their fears that any measures against Hamas in Gaza might involve attacks on innocent Palestinians or the spectre of communal punishment. Annoyingly to Israel's leaders, even US President Joe Biden has spoken as if he worries that restraint might not come naturally and used the occasion to affirm his belief in Palestinian rights and a two-state solution to the Middle-East's most intractable, perhaps unsolvable, problem.

No friends of Israel doubt that it has been provoked in a terrible, and unforgivable way. It has a just cause, even if its hands are far from clean - have not been clean for 75 years. Few observers would doubt that any Hamas operatives encountered in Gaza face a horrible fate. Most doubt that the organisation can be destroyed, or that the hatred and violence it has visited on its own people as much as Israelis can be completely extirpated. Many fear that Israel will interpret Palestinian anger and frustration at their lot as support for the bullies who ran their city, badly.

There's an Israeli mood for a reckoning. With some of the more belligerent leaders, such as Benjamin Netanyahu, perhaps a feeling that he can salvage from the unity and outrage political survival for himself, despite his and his government's acts and omissions that have kept disputes on the boil, while neglecting to recognise the danger they were facing.

A real option is to stop the siege and bombing now, with a measured move on Hamas, rather than a boots-and-all operation.

One question Israel must contemplate is whether, for once, it really needs go to war in any serious and no-quarter way at all. Do nothing, or next to nothing further, is a real option. Perhaps a strong one that would infuriate and expose its enemy.

For once, after all, Israel's short- and medium-term future is not in issue, as it was during wars with Arab nations in 1948, 1956, 1967 and 1973. Nor could it claim to be facing a sustained existential threat, in the way it said it was when it invaded Lebanon. Israel itself had insisted that regular rocket attacks from Hamas were a nuisance but not one that had even warranted any sort of mobilisation.

There are some who might suggest that if Israel does not react in a decisive and crushing way to this - the greatest loss of Jewish life in Israel on a single day - it would be interpreted as a sign of weakness, fear or loss of will and might even lead to further massacres in which Hamas tries to raise the stakes until Israel is forced to respond, perhaps not on such favourable terms.

Against this is the undoubted fact that Hamas wants and expects a massive overreaction from Israel, including further long-term oppressive and repressive controls over the Palestinian population. It wants to provoke group punishment, if only because it believes that this will heighten existing grievance and thirst for action by Palestinians and their friends. Already Israel's plan for a land war is accompanied by nervous talk about whether Hezbollah might respond to an armoured invasion of Gaza by action on Israel's northern borders.

In strict military terms, Israel is, of course, more than capable of handling that as well as the punishment of Hamas and Gaza. Its formidable arsenals are topped up by the United States, and vastly superior intelligence and communications capacity. It has repeatedly shown the capacity to strike fast and decisively, resilience in the case of setback, and vastly superior military discipline and morale.

But an invasion of Gaza, street by street fighting, military occupation and government, and coping with an angry and frustrated, but not too intimated population, does not involve playing to Israel's particular skills. That sort of fighting, even more than non-stop air and missile raids, involves a lot of resources and a lot of manpower - the more taxing with a part-time army otherwise involved in the economy. American and European assistance will not extend to active involvement.

No doubt the shock, awe and fundamental injustice of the Hamas massacres has put further iron in the Israeli soul and a firm determination to see matters through. But doing so may take time and a lot of energy. Soldiers and police, those who will be most involved, have shown increasing weariness with the non-stop struggles with a hostile population being badly treated, including by settlers acting with the connivance of the government. Many in the armed services have been suspicious of the motives of Netanyahu and his right-wing fundamentalist ministers, particularly about whether they have any practical vision for (or intention to create) a negotiated settlement. This is not to suggest that the military is anywhere near mutiny, but in Israel political crisis and dubious conduct can create inefficiency and a want of unity of purpose.

Israel's war planners have been slow and deliberate in preparing for the land invasion, despite some initial impressions that it would be a prompt boots-and-all operation. They are also, no doubt, calculating risks - which include incursions and missile attacks by Hezbollah from Lebanon, and civil uprisings, perhaps on the debilitating intifada model by Palestinians around the West Bank. There is the risk of mischief by Syria and Iraq, and of engagement with Iran and its agents. There is also the prospect of Palestine's again becoming a cause for Arabs and Muslims around the world. Once that was not uncommon, but over recent decades the cause of the Palestinian people became somewhat of a bore for groups such as al Qaeda in Afghanistan and Iraq, IS in Syria and Iraq, and Islamist rebels in Africa and Southeast Asia. The prospect of some sort of final showdown, the greater for the size of the Israeli commitment, may prove irresistible for committed warriors unafraid of suicidal action. Those impulses may be manipulated, for mischief or serious secondary purpose by people wanting to enmire the US, its allies, or even Russia in side-struggles. Neighbours jostling over regional alliances and quarrels, and liberation movements about the world, may also make the conflict more dangerous, unpredictable and long-lasting.

It is already obvious, for example, that the prospect of war assists Russia in its war with Ukraine and may affect American plans to expand NATO and make it more effective as an instrument of offence, rather than defence, against Russia.

Iran, which has been funding and supplying Hamas, and the Lebanese group Hezbollah, is already a bit player in the war with Hamas. But decisive military action against Hamas in the middle of the population of Gaza increases the risk of the conflict spreading beyond the borders of Israel and Gaza, including through direct attacks on Israel and Iran. Arab nations which have made their peace with Israel, such as Egypt, Jordan and some of the Gulf States, and countries such as Saudi Arabia may be reluctant to get involved through top-down decisions. After Yemen and Libya, they would see the risks of getting dragged into a war based on street fighting, with no obvious outcomes. But the very nature of their authoritarian rules makes them susceptible to the mood of the mob and populist religiously oriented causes.

Open conflict in Arab states, including Iraq and Syria, creates groupings wanting to get involved in jihadist struggles, or those using the Palestinian problem as an alibi for their own conflicts with local religious and political authorities. Some of these have continuing links with Islamic State or Daesh - indeed Israel insists that Hamas should be seen as an Islamic State organisation. If this is so it underlines how foolish the actions of Israel over recent decades to use Hamas's rise to power in Gaza as a means of undermining the Palestinian Authority.

It is Israel, rather than Hamas that has used the more "Now or Never" language suggesting that a war will end the Hamas problem, once and for all. But of course, it will not. On the face of it, for example, the war will leave continuing problems of Israeli occupation of Palestinian lands, and Palestinian refugee camps in Israel, in Jordan and Lebanon, unaffected. That is a potent and continuing conflict, even if Hamas, and the surrounded Gaza city state, are to be regarded as a special case.

Many of the people of Gaza fear that Israel has a secret secondary agenda of expelling the Inhabitants of Gaza into Egypt in a second Nakba, the 1948 way by which perhaps 300,000 Palestinians fled war and Jewish massacre or sought temporary refuge outside old Palestine - and were never allowed to return. That all Jewish people anywhere in the world have a "Right of Return" - aggravates the sense of injustice. When Israel warns ordinary citizens of Gaza - people uninvolved with Hamas - to the south of Gaza - it denies an intention to expel. But it may effectively serve to create a pile of rubble physically incapable of sustaining the population.

The hard and tough policy is justice. For Israel's victims. For innocent Palestinians. And for those accused of being with Hamas.

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It is also, of course, by no means clear how Israel plans to identify Hamas members or supporters, whether among those heading south or those who stay. Experience with other efforts to weed out insurgents in other places show that many people - including complete innocents - stay rather than flee, and that guilt cannot be presumed. Nor has Hamas belligerence yet suggested some idea of pitched battles of resistance, at which superior armour can be decisive. More probable, in prospect, are house by house searches, occasional gun battles, major use of improvised explosives, and not a few ambushes and death traps. Any justice visited would have to be open and transparent to a suspicious world.

To me, the most persuasive argument for a smaller and more restrained response is the simple fact that Hamas wants a massive over-reaction and believes this will serve its cause. It is very hard to believe that Hamas accurately reflects Palestinian opinion or will, but it is easy enough to assume that it understands the local politics of the struggle. Rather better than the Israelis anyhow. They have consistently misunderstood the cause or the strength of the feelings behind it. Their fabled intelligence services failed to predict or anticipate the Hamas atrocities, or the extent to which they were indifferent to international opinion and calculated to enrage and inflame Israelis to an ill-judged reaction. One can understand that the bitter bereaved - indeed all of Israel - have an instinct for a response that is utterly "firm". And loud, shocking and awesome, to show the world and Israel's enemies that the nation will not be intimidated, terrorised or distracted from its purpose.

To such brave words, one could only ask why that involves doing just what the enemy wants. Israel may be rather impatient with the international prioritisation of demands for justice for Palestinians, and the avoidance of war crimes, over demands for justice for the Israeli victims of the Hamas massacres. In the end, however, Israel's capacity to do anything in the way of justice for its innocents depends very much on its capacity to do justice for Palestinian innocents.