A Palestinian woman is standing in her kitchen when she hears a deafening bang. Rushing to her living room she sees her family in pieces, spread across floors, walls and ceiling. The horror is total and meaningless. Nobody meant it to happen, so what was its cause?

The tragedy in Gaza surely marks the time when the world declares air-launched bombs and long-distance shells to be illegal under the 1983 Geneva convention. They should be on a par with chemical munitions, white phosphorous, cluster bombs and delayed-action land mines. They pose a threat to non-combatants that should be intolerable even in the miserable context of war.

I can accept Israeli claims that they are not intentionally targeting civilians in Gaza - or the United Nations base set on fire yesterday. But the failure of their chosen armaments had the same effect. The civilian death toll is now put at 673, mostly women and children.

It is barely conceivable that the most accurate weapon of war, an infantryman, would deliberately enter a house and massacre unarmed women and children as they have their dinner. As a result, mercifully few do. When such cold-blooded murder is committed, from the 1968 My Lai killings in Vietnam to those now coming to light in Iraq, we are appalled, and inquiries, trials and disciplinary procedures follow.

Those killing from the air need have no sight of the carnage they unleash. They are placed at both a geographical and a moral distance, with a licence allowed no soldier on the ground. Whether they are dispatching free-fall bombs or GPS-guided missiles, tank shells or predator drones, Hamas's Qassam rockets or improvised explosive devices, they know they often miss their targets, but they launder any carnage as "collateral damage" and leave politicians to handle the backlash. The soldier shrugs and walks away, with no obligation to humanity beyond the occasional apology and a reference to the other side being just as bad.

If gas, landmines, chemical weapons and cluster munitions are now banned - a ban broadly obeyed by most civilised armies - why not aerial bombardment? Instead, bombing is becoming ever more prevalent. It precedes any operation, as a sort of overture, and eagerly takes part in each tactical twist. Counter-insurgency war, in Iraq and Afghanistan, has seen western armies take heavy casualties. But such is the political aversion to them that Israeli, American and British ground forces operate under strict "force protection" rules to minimise losses.

This has led to the reckless use of stand-off munitions, as regularly reported by embedded correspondents. Rather than employ infantry to clear an apparently hostile settlement, commanders call in air strikes and pound it to rubble. The Israelis have responded to the Hamas bombardment of their towns with a far heavier bombardment of Gaza. Both endanger civilians to a degree that cannot be other than criminal. That human shield tactics may be involved is no excuse: the law does not permit the killing of innocents in the hope of reaching the guilty.

The bombing of urban infrastructure is an act of terror, meant to weaken the resistance of victims and cause them to surrender. This was the case with the west's bombing of Belgrade in 1999 and Baghdad in 2003, the latter under the openly terrorist rubric of "shock and awe". Neither achieved the ambition proclaimed by the champions of air power, Bomber Harris's promise "to win the war from the air".

In an extraordinary article on these pages yesterday, David Miliband declared the title "war on terror" to be "misleading and mistaken". It apparently "gave the impression of a unified, transnational enemy, embodied in the figure of Osama bin Laden and al-Qaida". In reality terrorism was a disparate phenomenon, often internal to state politics. Besides, wrote the foreign secretary: "Terrorists succeed when they force countries to respond with violence and repression."

Miliband is right. But those who have been saying this since 9/11 wonder what has caused this sudden conversion. Did Miliband protest when Tony Blair reportedly pleaded with George Bush to be the first to bomb Kabul in 2001? Is this the same Miliband who sat silent as a member of the government that supported "shock and awe"? Is he now pleading with the Americans to stop using weapons against the Pashtun - such as aerial assassination - that exacerbate both war and terror?

The truth is that the war Miliband is still waging against militant Islam has been conducted largely by weapons of terror, namely bombs and long-distance artillery shells. They have killed untold thousands of non-combatants since the "war" began in 2001 - a violence far more devastating than the Israelis have inflicted on Gaza - destroying unimaginable numbers of homes.

In his book Shock of the Old, the science historian David Edgerton cites the bomber as the most overrated of all weapons of war. Glamorous, noisy, ostensibly sophisticated and easily marketed to "techno-dazzled" generals, it has proved an ineffective killing machine. Its use against the perpetrators of terror is a classic of soldiers fighting the last war but one.

In Vietnam, Serbia, Lebanon, Iraq and Afghanistan, those deploying bomber power constantly promised more than they could deliver, as they did before D-day. As Correlli Barnett has remarked, as in Vietnam and Kosovo so now in Gaza, the airman's bombast, that he could terrify the enemy into surrender, must be rectified by troops on the ground. Time and again the bomber has been outgunned by the AK-47.

No weapon fired at a distance can be sure of its target. As Colin Powell once said, the phrase "tactical surgical strike" had him racing for the protection of his bunker. All the electronics in the world seem unable to prevent constant friendly fire deaths. Meanwhile, the dominance of air forces in procurement battles has left Britain's land army woefully under-equipped.

In modern asymmetric warfare inaccurate munitions are worse than useless, they are a gift to enemy propaganda. In the present Gaza turkey shoot, the Israelis cannot have intended to hit the UN, knowing the impact it would have on world opinion. But once embarked on the campaign they clearly cannot discipline themselves.

In Afghanistan the American commander, David Petraeus, is said to regard his own side's bombing of villages and wedding parties as utterly counterproductive. Yet once forces are deployed, with ground and air in partnership, they seem beyond all command and control. They illustrate Liddell Hart's comment on military technology, that "the progress of weapons has outstripped the minds of those who wield them".

If Israel fails to win its political objectives in Gaza, it will in part be because of its massively destructive attempt to terrify the Palestinians into surrender from the air. Every errant missile explodes on the television screens of the world.

In the complex politics of war, these weapons are like torture. They numb moral sensibility and do harm beyond all justification of victory. They should be abolished. If we wish to kill other people for whatever reason, we should use only weapons that kill the right ones.

simon.jenkins@theguardian.com