Leading article: An opportunity for peace that must not be squandered

The Arab Spring has delivered yet another unexpected twist. Fatah and Hamas, the two warring factions of Palestinian politics, have agreed to a unity deal. The Israeli Foreign Minister, Avigdor Lieberman, claimed yesterday that the two leaderships were panicked into the deal by popular revolts across the Arab world, implying that Fatah and Hamas face the same sort of internal opposition as Hosni Mubarak in Egypt and Bashar al-Assad in Syria. This is not very convincing. The unification is actually very popular among Palestinians. There were demonstrations in Gaza earlier this month calling for such a political reconciliation.

And it is the Israeli government that gives the greater impression of panic. The Israeli Prime Minister, Benjamin Netanyahu, has responded to the deal by evoking the spectre of Hamas taking over the West Bank as well as Gaza. And Mr Lieberman has issued wild threats to withhold the delivery of tax revenues that Israel collects on behalf of the Palestinian Authority.

The consequences of this reconciliation for the peace process are, as yet, unclear. Theoretically, it should be a positive development. Palestinian political unification will undercut the familiar argument from the Israeli side that, with the Palestinians divided politically, there is no credible partner for peace. It could also supply extra momentum to the Palestinian bid to win recognition for a state (within the 1967 borders) in the United Nations General Assembly, planned for later this year.

Yet, in practice, the incorporation of Hamas ministers into the Palestinian government will also give the Israeli government a fresh reason to resist pressure to hold serious negotiations. While Mr Netanyahu had no good reason to refuse to deal with Fatah, Hamas's refusal to renounce violence gives him free rein to be obstructive. It is too difficult to say at this stage which force – the drive for unity, or the anti-Hamas reaction – will prove the stronger.

Much will depend on the question of how far Hamas is willing (or able) to moderate its official position with respect to Israel. Does this deal indicate that the group's leadership is prepared to sign up to the preconditions that have long been demanded of it by the international community, namely to renounce violence, to recognise Israel and to respect previous treaties?

The response of the international community will also be important. The United States and the European Union must decide whether to welcome the unification as a positive development, or to adopt the knee-jerk hostility of the Israeli government. The initial reaction from Democrat and Republican legislators in America, where both have echoed the Israeli response, has been disappointing. But the reaction from European capitals has, thus far, been less negative. That is an encouraging sign.

The EU made a serious mistake in the wake of the 2006 Palestinian elections, when it agreed, under Israeli and US pressure, to make ultra-strict demands of the victorious Hamas in exchange for recognition. Rather than working with the legitimately elected Hamas administration, the EU helped to push it on to the sidelines. After five years, it should be clear to all that freezing Hamas out of negotiations is not going to make the movement disappear. The history of all previous intractable conflicts demonstrates that peace comes through sitting down with enemies, not ostracising them.

The Middle East is in ferment. Regimes that looked rock-solid only months ago are tottering. Assumptions across the region are being challenged. This creates dangers, but also opportunities. Israel and the international community should seize the opportunity that they missed five years ago and attempt to lock Hamas into a peaceful negotiation process.