Whatever else can be said for or against Israel's escalation of military action against Lebanon, there is little prospect that it will achieve its stated objectives. If Israel couldn't defeat Hizbullah after 18 years in which its army occupied large swaths of Lebanese territory, it is not going to succeed with air strikes and blockades, or even another occupation. The same point applies even more forcefully in the case of Gaza. Every time Israel applies the iron fist in an effort to beat the Palestinians into submission, their resistance simply re-emerges in a more extreme and rejectionist form. Far from fearing Israel's wrath, Hizbullah and Hamas must be rather pleased at their success in provoking it into the sort of over-reaction from which they have always benefited.

Nor does it seem plausible that military action will enable Israel to secure the release of its captured soldiers. The civilian victims of Israel's indiscriminate retaliation have no real influence over the militias that hold them, while the militias themselves are untroubled by the spectacle of public suffering. On the contrary, they thrive on it. In the case of Lebanon, it is possible that acts of collective punishment, such as the destruction of Beirut airport and yesterday's killing of yet more civilians, might divide Hizbullah and its supporters from the rest of the country, but only at the risk of triggering another civil war and creating a vacuum that Israel's enemies in Syria and Iran will find easier to exploit.

In view of all this, it is valid to ask what Israel thinks it is doing. Indeed, this question is implicit in the statements of world leaders at the G8 and elsewhere who have called on Israel to use force proportionately, avoid civilian casualties and refrain from acts that might strengthen Hamas or destabilise Lebanon's fragile political settlement. No one quibbles with Israel's right to defend itself, but doesn't it understand how irresponsible and immoral it is to deliberately escalate the conflict in this way?

The problem is that the premise of the question is false. It assumes that Israel shares our view that a de-escalation followed by negotiation is the best route to a settlement. It assumes, therefore, that when Israeli ministers complain of having "no partner for peace", they actually want one. A much more sensible approach would be to credit them with having the intelligence to know exactly what they are doing and to work backwards from there.

If so, it might become apparent that far from wanting a partner with which to negotiate, the Israeli government is acting with the specific intention of forestalling that possibility. There is nothing particularly new in this. The extremists on both sides have always formed a kind of tacit alliance, with the supporters of "greater Israel" and "no Israel" understanding their joint interest in preventing any moves towards a compromise peace. That is the main reason why Israel encouraged the growth of Hamas as it emerged in the 1980s. Unwilling to negotiate with the secular nationalists of Fatah, even as they were moving towards support for a two-state solution, the Israeli authorities thought it would be a clever idea to promote their Islamist rivals.

In the case of the current crisis, it is no accident that it occurred at precisely the moment when the Palestinian president, Mahmoud Abbas, was gaining the upper hand in the latest round of that struggle. By using the threat of a referendum to force Hamas to accept the existence of Israel as the basis for a final settlement, Abbas had created the most promising opening for peace in six years. Faced with internal division and the loss of political initiative, Hamas militants understood that the only way to prevent it would be to trigger another cycle of violence. In turn, the Israel government, whose interests were also threatened by the Abbas initiative, recognised that it had an equally good reason to oblige. The effect of Hizbullah's intervention and Israel's over-reaction has been to put peace even further down the agenda.

The plain truth is that Israel thinks that it can get more by imposing a solution through force than by negotiation and is not interested in any kind of peace process. The Israeli prime minister, Ehud Olmert, pays lip service to the road map, but he has already received American endorsement for his fallback position, artfully dubbed "unilateral convergence". George Bush has described it as a "bold idea". Armed with the knowledge that he will continue to enjoy American patronage if the road map fails, Olmert has set out to ensure that it does just that. Bush's diplomacy has been truly inept.

It's high time western governments grasped the fundamental truth that Israel is pursuing an agenda that conflicts directly with their own. In the context of the fight against terrorism and the need to promote international cooperation, the west's interest must be to remove the Palestinian question as a source of grievance among mainstream Muslims in a way that guarantees justice for the Palestinians and security for Israel. A settlement of this kind is perfectly feasible and has been outlined in countless documents and initiatives over the years, most recently in the Geneva accords. But the main reason it has proved illusive is that Israel is not, and never has been, prepared to make the territorial compromises required. It still believes that it is entitled to the victor's spoils by annexing large tracts of Palestinian land.

This situation will persist as long as the west remains in denial about the reasons for the ongoing conflict and until the Israeli political establishment is forced to pay a price for its obstinacy. Yet the US remains entirely complicit in its role as Israel's main strategic ally. In the midst of last Friday's onslaught, in which Israeli bombers killed dozens of Lebanese civilians, the Pentagon announced the export of $210m of aviation fuel to help Israel "keep peace and security in the region". Even Britain and other European countries indulge in a form of diplomatic misdirection by focusing one-sidedly on the roles played by Syria and Iran.

The key to resolving the situation in Lebanon lies, as it did throughout the 1970s and 1980s, in finding a solution to the Palestinian question. A viable and successful Palestinian state would rob Hizbullah and its sponsors of the conceit that they are defending helpless Muslims and make it easier for those in the region who oppose them to gain the upper hand. Mahmoud Abbas is the only leader currently working for the kind of negotiated two-state solution the Middle East and the wider world desperately need. But he is being let down by the west at the moment when he had earned the right to expect better. The Palestinian president needs a partner for peace. If Israel will not play that role, the international community must.

· David Clark is a former Labour special adviser at the Foreign Office dkclark@aol.com