The agreement between Fatah and Hamas, following secret talks sponsored by Egypt, has the potential to end years of Palestinian division, infighting and paralysis.

The pact promises an interim "unity" government until elections next year. The Palestine Liberation Organisation (PLO) will be restructured to incorporate Hamas, creating a common front for the next stage of struggle against Israeli colonisation.

This common purpose between Fatah and Hamas is fragile, however, because it is contingent on so many forces that have brought the two sides together. Both sides had good domestic political reasons to make this agreement, but it is also the product of unique circumstances in a changing political landscape.

The Palestinian people have for some time been demanding a united front against Israeli colonisation and western complacency, a demand that puts pressure on both Hamas and Fatah.

And leaked details of negotiations between Israel and the Palestinian Authority (PA) pushed the PA to take a tougher line to hold its public support.

Then there are regional factors. Hosni Mubarak of Egypt had long pressed the PA to go along with Israeli and American demands; Mr Mubarak's fall gave the PA president, Mahmoud Abbas, room to manoeuvre.

The new Egypt can already be seen to be very different from the old on the whole issue of Palestine. The foreign minister Nabil al Arabi says Egypt's border with Gaza will open soon, and that the old policies vis-à-vis Gaza were a shameful episode in Egyptian history.

Hamas, too, finds regional developments bringing it new cause for flexibility. Their patrons in Damascus, having a bad time internally right now, may be distracted or may have decided they are better off with less regional involvement.

Leadership struggles within Iran mean that it also has too much on its plate, and like Syria needs to concentrate on internal problems.

So both Hamas and Fatah find themselves more free than previously to move towards the unity the Palestinian people want.

Israel has also helped, no doubt inadvertently, with its attacks on Gaza, colony building in the West Bank and house demolitions in East Jerusalem. More generally, Israel refuses to come to terms with a possible peace with the Palestinians and Palestinian statehood. Meanwhile, US backing for Israel did not encourage the Palestinian leaders to keep waiting.

Reaction to the Hamas-Fatah agreement varied. Palestinians welcomed it, of course, as did the Arab League. But the Israeli government condemned the pact, the US government was generally negative and rumbled its warnings, and European capitals were pessimistically hesitant - all of which is revealing.

The interim deal is no guarantee. Both Hamas and Fatah are capable of political machinations which could doom the accord. We will see how well the leaders in both parties understand the changing dynamics in the region, and the revolutionary spirit among Arab people, a spirit that will no longer accept the old political cynicism and corruption.

We must also wait to learn how the Israeli, American and European governments will read and react to the changing regional dynamics. The next chapter in Palestinian history will be defined by the interplay of all these factors.

Israel, the US and EU will keep pressing the Palestinians to more or less maintain the status quo, but the Palestinian people, especially the young, will respond to regional changes by pushing their leaders for real change to restructure the PLO and end the "peace process" of the last 20 years.

They will want to move towards collective decisions on central issues such as the status of Jerusalem, refugees and right of return, and real sovereignty.

As required by the agreement between Fatah and Hamas, any new Palestinian government must show independence from any single political group. This may mean replacing figures such as the PA prime minister, Salam Fayyad, who is close to Fatah. The leadership will also have to be attentive to the public's voice on a new group of "technocratic" leaders.

Mr Abbas apparently continues to favour diplomacy in the struggle with Israel. But others are entertaining different methods of popular resistance against Israel in the Occupied Territories, such as the weekly non-violent Bil'in protests against the Israeli separation wall. Both methods will be needed to provide the Palestinians with the power to shape relations with Israel.

Palestinian leaders can be effective if they can heed the regional winds of change, and if they follow the Palestinian public's call for renewed popular resistance against Israeli colonialism.

Magid Shihade is an assistant professor of International Studies at Birzeit University in the West Bank