The United States has sent a top envoy to Israel to try to revive talks on a Middle East zone free of nuclear weapons.
The issue is a sticking point in a landmark Nuclear Non-Proliferation Treaty review conference in New York that some fear will end on May 23 without progress on global disarmament.
Officials said Assistant Secretary of State Thomas Countryman was in Israel to discuss the issue.
Establishing a nuclear-free zone in one of the world's most tense regions is a rare point of agreement between the United States and Russia.
Frustrated by the delay of UN-led talks that were supposed to take place by 2012, Russia has proposed the talks be held no later than 2016.
Egypt and Arab states contend talks should be held with or without Israel.
That has alarmed Israel, which is not a party to the treaty and has never publicly admitted what is widely believed -- that it controls the Middle East's only nuclear arsenal.
Israel was furious when the United States five years ago agreed to talks by 2012.
The United States is seeking a compromise that satisfies Arabs but does not alienate Israel.