Israel and Palestinians lay groundwork for new peace talks, says John Kerry John Kerry steps out of a helicopter in Amman back from the West Bank city of Ramallah (AFP) There was no immediate formal response from Israel. But one Israeli official indicated that the agreement was fragile. "We are talking about months, both to ensure the process is substantive and comprehensive, and to get us past September [when the UN general assembly meets]," the official told the Reuters news agency. The Palestinians have threatened to start unilateral measures such as applying to join the International Criminal Court if no progress is achieved by that date. Mr Kerry declined to spell out the terms for resumed negotiations and said the deal had yet to be formalised. "The best way to give these negotiations a chance is to keep them private," he said. We know that the challenges require some very tough choices in the days ahead. Today, however, I am hopeful. If everything goes to plan, it is expected that Tzipi Livni, the chief Israeli negotiator, and Saeb Erekat, her Palestinian counterpart, will travel to Washington perhaps as early as next week. Mr Kerry's announcement followed four days of gruelling diplomacy in which he met Mr Abbas three times in an apparent effort to persuade him to ease his conditions for meeting Benjamin Netanyahu, the Israeli prime minister. The attempt appeared doomed to failure after specially convened meetings of the Palestine Liberation Organisation and Mr Abbas" Fatah movement declined to give the Palestinian leader the green light he sought. Senior Palestinian leaders had demanded that negotiations be based on borders that existed before the 1967 Six Day War, when Israel took control of the West Bank, east Jerusalem and Gaza. Israel has refused to accept the pre-1967 borders as a starting point because it wants to keep large settlement blocs it has built on land the Palestinians claim for a future state. Mr Erekat informed Mr Kerry of the Palestinian position in Amman. Rather than leave empty handed, the US secretary of state flew by helicopter for a third meeting with Mr Abbas. One Palestinian source told The Telegraph that Mr Abbas relented after Mr Kerry agreed to provide a clear guarantee that the negotiations are supposed to result in a Palestinian state. "The guarantee is about ensuring the establishment of the Palestinian state, within the 1967 borders," the source said. Of course the leadership will accept the principle of exchanging land.