U.S. officials reacted skeptically Monday to an Israeli proposal that the United States and other world powers guarantee that a new nation of Palestine remain demilitarized as a condition of its statehood.

Israeli Prime Minister Benjamin Netanyahu said for the first time Sunday that Israel would be prepared to live side by side with a Palestinian state, but only if world powers guaranteed that it would be "demilitarized." The proposal came in a major statement of his views on the Israeli-Palestinian conflict that attracted attention worldwide.

But U.S. officials expressed reluctance Monday to take part in such a plan, and said that, in any case, the Palestinians probably would not agree to it in negotiations.

"We take the security of Israel very seriously, but we need a solution that works, and this would be very difficult for the Palestinians to swallow," said an official, who declined to be identified because of the sensitivity of the diplomacy. American officials "are a long way away from the point where we'd be talking about this kind of arrangement."

He noted that Netanyahu provided no specifics about what would be a complex task. Netanyahu has said previously that Israel could not agree to the creation of a Palestinian state that possessed a military, had full control of its borders or wielded authority over electronic communications.

Despite the criticism, U.S. officials were generally positive about the speech, suggesting that it represented another step toward the high-level negotiations they want to see begin soon between Israelis and Palestinians.

They hailed Netanyahu's acceptance of the idea of a separate Palestinian state, despite the conditions. U.S. officials were willing to overlook the fact that Netanyahu did not agree to the Obama administration's insistence on a complete halt in the growth of Israeli settlements in Palestinian territories.

Palestinian officials bristled at Netanyahu's speech, but U.S. officials portrayed the speech as simply laying out the Israeli opening position in what was likely to be a protracted discussion.

"It's going to be a complicated negotiation," said Ian Kelly, the State Department spokesman.

Netanyahu said in his speech that the Palestinians would need to recognize Israel as a "Jewish state," a comment that was widely taken to mean there would be no right of return for Palestinian refugees.

But Kelly said U.S. officials took the view that it meant only that "the Palestinians need to recognize the right of Israel to exist."