A fortnight ago Gaza was taking a pounding, following the Hamas capture of an Israeli soldier, and the rest of the world — including, crucially, the Arab states — had done nothing. Cue Hizbullah, spotting its chance to assert itself as the Palestinians’ champion and lead force of Arab resistance — so boosting its legitimacy in the eyes of the Lebanese people. It therefore mounted its own raid, abducting two more Israeli servicemen.

Meanwhile, standing behind Hizbullah were its two patrons, Iran and Syria, both aware that there is always domestic and regional popularity to be gained by standing up to Israel and, therefore, the US. Both were keen, too, to show that they can inflict pain as well as absorb it, and Hizbullah is their weapon.

On the Israeli side, several critical elements also came together. First, Israeli anger at Hizbullah had been building for a while; it did not start with last week’s kidnapping. As the columnist Yoel Marcus, of Ha’aretz, puts it: “Day in and day out, Israel has been subjected to raids, ambushes and kidnappings.” Hizbullah is not a ragtag army, hurling stones. With Iranian help, it has built a formidable arsenal, including guided and long-range missiles.

Second came the nature of the provocation. Both Hamas and Hizbullah captured soldiers. To outsiders, that would seem to be fair play under the rules of guerrilla warfare. But soldiers carry an almost sacred status in the Israeli imagination. The Israeli Defence Force (IDF) is a conscript army, so the rhetoric about “everyone’s son or daughter” is literally true.

All that led to intense public pressure. Professor Eyal Zisser of Tel Aviv university says Israelis could not tolerate “military failure” against both the Palestinians and Hizbullah: “There comes a point when you cannot stand it any more.” Some governments might have been able to resist such pressure.

But not this one. For Israel is now led, for the first time, by both a PM and defence minister whose path into politics did not go through the army. Ehud Olmert and his coalition partner, the Labour leader Amir Peretz, are military novices. Both have something to prove. Olmert and Peretz need to assert themselves. Hence Olmert’s declaration that “we will demolish them and nothing is going to hold us back”. Or the defence minister’s vow that the Hizbullah leader “Sheikh Hassan Nasrallah will remember the name ‘Amir Peretz’ for the rest of his life”. In that mood, neither man was likely to rein in Israel’s ambitious chief of staff, Dan Halutz. Instead, say the Israeli commentariat, there are “three Napoleons” running the show.

What might make this storm pass? A first, essential element is a swap of prisoners. Officially the freeing of its captives was Hizbullah’s initial motive, so progress in that area coupled with the return of Israel’s men would allow both sides to step back and save face. But Israel will not move until it has gone some way to achieving its larger objective, which is the weakening of Hizbullah. The current crisis has handed Israel an opportunity to do so. One report suggested the IDF needed another 48 hours to reach that objective.

Once satisfied that it had hobbled Hizbullah, Israel might well agree to an international military presence on the Lebanese border. Both sides would exchange their prisoners and hold their fire.

Such a plan might work, bringing an end to the mayhem of the last few days. But even if resolved soon, this episode will have a lasting impact. It could fatally undermine the project that defines Ehud Olmert: unilateralism. Picking up where Sharon left off, Olmert aims to draw Israel’s final borders himself, free of the inconveniences and hazards of negotiation with the country’s neighbours. So far there have been two precedents: Israel’s unilateral withdrawal from southern Lebanon in 2000, and from Gaza in 2005. But have these withdrawals brought quiet, let alone peace? They have not. On the contrary, they are the sites of the current violence.

This could lead the Israeli right to declare that such retreats make no sense, that they only embolden the country’s enemies who merely pocket the yielded territory and carry on fighting. The Israeli left, meanwhile, might recover its interest in the search for a negotiated peace. From both the left and right, the logic of unilateralism has been eroded by the current crisis.

The greater legacy is the human one. Every bomb dropped by Israel will have broken hundreds of Lebanese hearts. The bereaved families of Israeli civilians will feel the same way about their enemy. From all the rational, strategic calculations, this is the factor that is so often missing: the hatred sowed in the human heart. Both sides have ensured this dreadful conflict spreads, not just across borders — but down the generations. — The Guardian