Israeli Prime Minister Benjamin Netanyahu arrived at the White House today, after warning the United States should not be duped by Iranian 'sweet talk' and charm.
Netanyahu was expected to tell President Barack Obama that a diplomatic solution to Tehran's standoff with the West must include the dismantling of its nuclear programme - a more demanding position than Washington's own.
His limousine pulled up at the West Wing of the White House, as chants of "try Bibi for war crimes" rang out from protesters across the street who used the Israeli leader's nickname.
The Oval Office talks with Obama threatened to open new tensions in an often testy relationship, which both sides tried to put on a more friendly footing when the US leader visited the Jewish state earlier this year.
Netanyahu arrives as the US capital digests the impact of a startling diplomatic opening which has followed the election of President Hassan Rouhani, and a historic phone call between Obama and the Iranian leader on Friday.
Obama said the conversation had convinced him there was genuine hope of a "resolution" of Iran's dispute with the West over its nuclear programme but would require "meaningful and "transparent" action by Tehran.
But Netanyahu has greeted Rouhani's conciliatory tone with deep skepticism and warned that it shields a desire to press ahead quickly with a nuclear weapons programme.
Israel's Channel One network reported that Netanyahu would tell Obama that Israel would abandon diplomacy if Iran's nuclear programme is not completely dismantled.
That position appeared to run counter to Obama's statement on Friday that Iran had the right to a "peaceful nuclear energy" programme if it lives up to international obligations.