The Middle East stands on the brink of catastrophe. The escalation of violence that has left hundreds dead in Lebanon and dozens dead in Israel has appalled the world. Judgement, however, is more difficult. Israel is under attack from two fronts, and was provoked in both cases by the deliberate kidnapping of its servicemen. Nevertheless the scale of damage inflicted in Gaza after the first attack from Hamas already raised questions about a disproportionate use of force and brought accusations of collective punishment; a war crime. This fades into insignificance compared with the wholesale wrecking of the Lebanese economy and infrastructure, so painstakingly rebuilt following years of conflict, after the second kidnapping.

Measured against the kidnappings alone, this must be rated as so disproportionate as to demand international condemnation in the strongest terms. But there are other more general strategic issues to take into consideration. The kidnappings were not isolated, but occurred in the context of sustained provocation. Hezbollah's rocket attacks from southern Lebanon rank as a major act of aggression, sponsored, by all accounts, by the Syrian and Iranian governments. Israel blames the Lebanese Government for the kidnapping of its soldiers and while many analysts say that this is unfair, it remains the case that the country's Government does contain Hezbollah members, adding weight to the Israeli case.

However, the fact remains that the majority of those who are suffering in Lebanon are not Hezbollah members, but innocent civilians. The Israeli Prime Minister's promise that the attacks will go on until Hezbollah is beaten is not realistic. Bombing its members will make them ever more determined.

Clearly Israel is caught in a terrible predicament. Its overall policy is the peaceful one of seeking negotiations with like-minded parties towards a fair and just two-state solution. The Palestinians might conceivably one day be brought to the table on that basis but Hezbollah, together with Syria and Iran, rejects Israel's very right to exist. That is the ultimate source of the present evil. The Israeli Government must hope that the ferocity of its reaction now will warn off its adversaries from countenancing even more dangerous adventures in the future. In calculating proportionality, Israel is entitled to take account not just of past aggression but of future threats. Nevertheless the cost in civilian lives on this scale must never be discounted as acceptable collateral damage.

Israel certainly has the right to survive and defend itself, as the G8 recognised at its recent summit, blaming Hezbollah and Hamas for the escalation in fighting and urging Israel to exercise restraint, a view also endorsed by Pope Benedict. A general Israeli ceasefire while rockets continue to rain down on northern towns and cities is not realistic, but it is not impossible to imagine it focusing all its military efforts on Hezbollah strongholds in southern Lebanon. Lebanon itself does not deserve the punishment it is taking. If the apparatus of government breaks down altogether, which is on the cards, it could crumble into lawlessness. A ruined and terrorist-dominated failed state on its northern borders is the last thing Israel - or the rest of the world - wants to see.