The unprecedented prisoner exchange today between Israel and Hamas will shift attention in the coming months to undermining the possibility of an upsurge in violence in the West Bank, where hundreds of Palestinian prisoners returned today after being released in return for Gilad Shalit.

After years of refusing a mass release of 1,000 prisoners, Prime Minister Benjamin Netanyahu last week decided to pay what he called a "heavy" price for the Israeli soldier, who has been in Hamas captivity in Gaza since being kidnapped in June 2006. A decline in violence between Israelis and Palestinians, both in in the West Bank and Israel, brought the risk down to a level that Mr. Netanyahu considered acceptable.

Analysts attribute the decline to a mix of factors: the construction of a barrier separating Israel and the West Bank, improved intelligence on Palestinian militants, and, perhaps most significantly, closer cooperation between the Israeli Defense Forces and the Palestinian Authority's security forces and police, which oppose a violent uprising and see Hamas as an enemy.

Security cooperation

Cooperation between the IDF and the PA is at an unprecedented level since the US began in 2007 overseeing reform of the Palestinian Authority's security forces, which have focused on tracking down Hamas activists and civil society organizations affiliated with the militant group. Keeping a lid on Hamas activity will be critical after the release.

"For their own survival [the PA] needs to keep a heavy hand on Hamas," says Yossi Alpher, the co-editor of Bitterlemons, an online Israeli-Palestinian opinion forum.

However, Hamas is very popular right now among Palestinians, even those in the West Bank, for securing the freedom of the 1,027 Palestinian prisoners, which puts the PA forces in a tough spot.

"It's conceivable there will be a wave of popular support for Hamas, and the security forces will be reluctant to intervene,’’ Mr. Alpher says. "Is it manageable or could it get get out of hand? It’s difficult to predict what is going to happen here."

He added that ever since the announcement of a reconciliation deal between Hamas and Fatah, which was never implemented, the PA security forces have been more lenient.

Concern behind the separation wall

The number of wanted militants has been whittled down significantly in recent years, according to Israeli military officials. In the days since the announcement of the deal, security officials have agreed with Netanyahu's assessment that the risk of releasing the prisoners is a manageable one.

"In terms of the assessment of Israel’s ability to prevent terrorist from attacks, there’s much more confidence," says Gerald Steinberg, a political science professor at Bar Ilan University.

However, although the release is supported by a broad majority of the Israeli public, many Jewish settlers living in the West Bank, where there is no separation wall intended to keep out potential terrorists, say they fear that the agreement will reenergize the militants who embarked on a campaign of violence against Israeli targets during the second Intifada.

As a precaution, Israel insisted in the agreement that 170 prisoners who hail from the West Bank would be deported to the Gaza Strip. Another 40 were deported to Egypt and eventually to Turkey, Qatar, and Syria. Israel rejected Hamas demands that a handful of its most senior military leaders be released.

"The last 10 years have been terrible," said Chaya Rund, a resident of the Jewish settlement of Ofra, northeast of Ramallah. "We don’t want to go back to that."