US President Barack Obama has urged Israeli and Palestinian leaders not to let the chance of a permanent peace deal "slip away".
"This moment of opportunity may not soon come again," he said, pledging US support for the new negotiations.
Mr Obama spoke the day before a new round of direct talks between Israeli PM Benjamin Netanyahu and Palestinian leader Mahmoud Abbas was due to begin.
Mr Obama spoke at the White House on Wednesday evening after meetings with Mr Netanyahu, Mr Abbas, Jordan's King Abdullah II and Egyptian President Hosni Mubarak.
His remarks came on the eve of the first direct negotiations between Israeli and Palestinian leaders in 20 months, which he said were "intended to resolve all final status issues".
Mr Obama said the goal of the talks, which are expected to last a year, was a permanent settlement that ended the Israeli occupation that began in 1967 and resulted in an independent, democratic Palestinian state existing peacefully beside Israel.
On Thursday, US Secretary of State Hillary Clinton is to hold discussions with the Israeli and Palestinian negotiating teams.
Mr Netanyahu and Mr Abbas are to then meet for the first face-to-face talks between Israeli and Palestinian leaders since late 2008.
US officials said they wanted to at least get agreement from the two sides to meet again, possibly in the second week of September.
Another meeting between Mr Obama, Mr Abbas and Mr Netanyahu could be held during the UN General Assembly at the end of the month.
Disagreement over Israeli settlement construction in the occupied West Bank has also threatened to cast a pall over the talks.
The Israelis have said they will not renew a partial freeze on building homes for Jewish settlers when it expires towards the end of this month, but the Palestinians say that without a freeze they will walk away from the talks.