The already extremely difficult Israeli-Palestinian negotiations became all the more difficult Wednesday with the announcement of Hamas-Fatah reconciliation.Soon after the pact, Israel called off a US-brokered meeting scheduled for Wednesday evening with the Palestinians to look for ways to extend the negotiations past the April 29 deadline.“Abu Mazen [Palestinian Authority President Mahmoud Abbas] needs to choose between peace with Israel and an accord with Hamas,” Prime Minister Binyamin Netanyahu said on Wednesday. “Abu Mazen chose Hamas, and not peace. Anyone who chooses Hamas does not want peace.”Netanyahu’s statement came following a meeting in his office on the proper response to the latest Fatah- Hamas stab at reconciliation.The prime minister has called a special security-cabinet meeting Thursday to discuss Abbas’s latest move and its implications.Abbas meanwhile responded by saying that the unity pact did not contradict talks with Israel, and that a Palestinian state living alongside Israel remained his aim.But in Washington, US State Department spokeswoman Jen Psaki said the US was “disappointed” by the move. Speaking at her daily press briefing, Psaki said US principles on the issue of Palestinian reconciliation have been consistent for decades: Any Palestinian government must “unambiguously and explicitly” commit to nonviolence, recognize Israel and accept previous agreements between the parties.“The timing was troubling,” she said of the unity pact, “and we were certainly disappointed in the announcement. Absent a clear commitment to those principle outlined, this could seriously complicate our efforts, and the efforts between the parties, to extend the negotiations.”Psaki said that “it is hard to see how Israel can be expected to negotiate with a government that does not believe in its right to exist.”She added the “ball is in the Palestinian’s court” to answer whether the three principles that have been long established will be met in the reconciliation pact.Psaki said there would “obviously be implications” by this move on US aid to the PA , and that the US was going to “watch and see what steps are taken by the Palestinians.”A senior administration official said the US was given no warning from the Palestinians that the announcement was coming, and that it was “not anticipated.”During a telephone call Wednesday evening with US Secretary of State John Kerry, whose fervent diplomatic efforts over the last year were dealt a severe setback by this accord, Netanyahu said Abbas’s latest move was no great surprise. The Palestinian modus operandi, Netanyahu told Kerry, was that as they get close to “decision time” they run away. This pattern has repeated itself numerous times in the past, he added, and when it looked as if the sides were closing in on finding a solution, “the Palestinians jump.”Psaki said that while Kerry did not speak directly with Abbas, the US team on the ground has spoken to him.It was not immediately clear whether the cancellation of Wednesday’s meeting was merely a one-day postponement, similar to last week when Israel deferred a planned meeting following the terrorist murder of Baruch Mizrahi on his way to Kiryat Arba, or whether Wednesday’s stalled session was part of what might be a much longer hiatus.Regarding efforts to negotiate a continuation of the diplomatic talks with the Palestinians beyond their deadline next Tuesday, Netanyahu said earlier in the day that every time the sides get close, Abbas adds new conditions “knowing that Israel cannot accept them.”On Tuesday, during a meeting with Israeli journalists, Abbas laid out his three conditions for continuing talks with Israel: That Israel release the fourth batch of Palestinian security prisoners, including Israeli-Arabs, and that none of them be deported; that Israel freeze all settlement construction; and that the first three months of the extended talks deal with the borders of a future Palestinian state.Israel has rejected those conditions.Justice Minister Tzipi Livni labeled the Fatah-Hamas accord as “very problematic,” and said it harms peace efforts that have been intensive and “an opportunity that has just recently been created.”Livni said Israel needed to assess the situation and weigh its future steps.Foreign Minister Avigdor Liberman said that Abbas needs to decide whether he wants to make peace, and with whom.“It is impossible to make peace both with Israel and Hamas,” he said. “Signing a unity agreement between Fatah and Hamas is signing the end of negotiations between Israel and the Palestinians.”Michael Wilner contributed to this report from Washington.