Robert Fisk: Bring in the peacekeepers? It's not as easy as it sounds

Do I hear the braying of the UN donkey in Gaza? On his Middle East tour, the French President, Nicolas Sarkozy, may well be mentioning that well-known Eeyore figure on the East River, always so willing to send its peacekeepers on Mission Impossible. The Palestinians have been trying to internationalise their conflict with the Israelis ever since Yasser Arafat pleaded for UN forces to protect the Palestinians after the failure of the Oslo agreement.

Always the Israelis have refused. The very odd observer force which the EU installed in Hebron after Baruch Golstein had massacred Palestinians at the mosque – its patrols regularly interrupted by the Jewish settlers of this very odd city – simply faded away. And the United Nations Relief and Works Agency has been throwing tents and food and school classes at the slums of Palestinian refugee camps for generations. Can it be that yet another Israeli failure in Gaza will change the dynamics of "peacekeeping" in the Middle East, that at last the ghost of Arafat will watch the "internationalisation" of the Israeli-Palestinian war?

The cliché, in both senses of the word – both the tired phrase and the matrix for any future UN force – is, of course, UNIFIL, the so-called United Nations Interim Force in Lebanon. It arrived in southern Lebanon in 1978 after Israel's hopeless "Operation Litani", which was supposed to "destroy" the Palestinian guerrilla forces north of the Israeli border. The UN mandate insisted that the Israelis retreat to their international frontier – which they refused to do – eventually leaving the UN with an Israeli occupation force to the south of them and Palestinian units with bases inside the UN force and to the north of them.

When Israel staged another hopeless invasion in 1982 – like its unrealistic Hamas operation in Gaza as well as the 1978 Lebanon invasion, it was supposed to "destroy" their Palestinian enemies – the UN found itself operating entirely within an Israeli occupation zone, even allowing Israel's intelligence officers to travel through UN checkpoints to arrest or assassinate members of the latest Lebanese militia to oppose the occupation in the south.

Only when Israel withdrew from Lebanon in 2000, 22 years after the UN's first arrival, did the peacekeeping force – now largely from poorer African and Asian countries – operate independently, albeit with Hizbollah now installed in their midst. The 2006 Israeli-Hizbollah war ended with a larger UN force in southern Lebanon, this time commanded by Nato generals who patrolled an area free of Hizbollah weapons – but only because Hizballah's newer long-range rockets could be fired from north of the UN's area of operations.

The UN force, it should be added, was constantly abused by Israel. It was accused of being "pro-Palestinian" (whatever that is), in league with "terrorists" (it was never explained how), weak, anti-Israeli and – of course – anti-Semitic. Israelis even accused a local UN Fijian commander of spreading Aids. So could there be yet another UN force in the region? Originally, there was a UN observer force on the Lebanese-Israeli border.

It arrived in 1948 and still exists – unarmed, on the frontier to this day, within the UNIFIL zone – and this, in reality, could be the framework of a new UN force in Palestine. In other words, an unarmed observer group rather than a peacekeeping force, which could add an international voice to ceasefire violations between Israel and Hamas. But be sure, the Palestinians would then ask for the same institution to be placed on the West Bank-Israeli border – and therein lies the problem for both Israel and the UN.

For which "frontier" would the UN then patrol? The UN border of the 1940s, the pre-1967 ceasefire lines – in which a pre-annexed East Jerusalem belonged to the Arabs – or the post-1967 border in which Israel claimed "annexed" Jerusalem, or the massive walled "frontier" which now bites deeply into yet more Palestinian territory – illegally in international law? And would the UN also have to "observe" the equally illegal Jewish settlements built on Arab land within the West Bank?

Gaza sounds an easy option. The UN could place some international troops around Gaza. But it would only be a matter of time before they would be required around the West Bank. That would be a Palestinian dream – and, for those Israelis who wish to continue their expansion into Palestinian land – a nightmare.