Attack hits Middle East talks hope

But already low expectations for the talks were jolted even before they began when a Palestinian gunman opened fire on an Israeli vehicle travelling in the West Bank, killing four passengers in an attack claimed by the militant Hamas movement. Israeli officials said the shooting was an attempt to sabotage the discussions.

With US officials allowing that success in Thursday's negotiations may be defined simply as an agreement to meet again, President Barack Obama was getting ready to host Israeli Prime Minister Benjamin Netanyahu and Palestinian President Mahmoud Abbas on Wednesday.

The goal is to formalise a peace agreement in a year's time that will lead to the creation of a Palestinian state. But with the two sides far apart on all the key issues, the going is expected to be slow and fraught with difficulties.

Tuesday's deadly shooting near the town of Hebron was a reminder of the fragility of the situation.

"We will not let the blood of Israeli civilians go unpunished. We will find the murderers, we will punish their dispatchers," Netanyahu said as he met with Secretary of State Hillary Clinton at a Washington hotel. "We will not let terror decide where Israelis live or the configuration of our final borders. These and other issues will be determined in negotiations for peace that we are conducting."

Netanyahu's spokesman, Mark Regev, said earlier that the attack would not change this week's summit, but served to stress the security concerns that Israel plans to make a central issue in the talks.

"There is no change. We are committed to peace," Regev said.

Later, West Bank settlers said they would break the government freeze on construction in their communities to protest at the shooting.

Israel imposed a 10-month freeze on construction in West Bank settlements in an effort to get negotiations with the Palestinians back on track.