President Barack Obama and Israeli Prime Minister Benjamin Netanyahu are meeting at a time that the three-decade estrangement between the United States and Iran may be nearing an end.
Obama and Netanyahu are set to meet Monday, and the White House said the two leaders would discuss negotiations with the Palestinians, developments in Syria and Iran.
The topic of Iran was likely to be one of the most contentious.
"I will tell the truth in the face of the sweet talk and the onslaught of smiles," Netanyahu said before boarding his flight from Israel to the United States on Sunday. "Telling the truth today is vital for the security and peace of the world and, of course, it is vital for the security of the state of Israel."
Obama spoke Friday with Iranian President Hassan Rouhani in the first direct conversation between the two countries' leaders since they broke off diplomatic relations after mobs in Tehran stormed the US embassy in 1979 and held a total of 52 hostages for 444 days.
The 15-minute phone call was a watershed diplomatic moment, suggesting that Rouhani — with Supreme Leader Ayatollah Ali Khamenei's permission — was interested in re-engaging with the West.
However, it also irritated Israel, a US-ally that has declared an Iranian nuclear program unacceptable and a threat to the region. Israelis derisively called Iran's efforts the "smiley campaign" and tried to persuade the United States not to be swayed by Iran's courtship, however persuasive.
"Negotiations are on the table to discuss various aspects of Iran's enrichment program," Iranian Foreign Minister Javad Zarif said Sunday in an English-language interview with ABC's "This Week."
It's a tempting offer for the United States, but one that could strain the already rocky relationship between Obama and Netanyahu over construction of new housing settlements, negotiations with Palestinians and even their personal feelings about each other that have occasionally spilled into public view.
The United States vowed to consult Israeli officials as it weighs a shift on Iran, and the two certainly would share intelligence, as they have done for years.
The US ambassador to Israel, Dan Shapiro, moved to calm concerns in an interview Monday with Israeli Radio.
"I think there is nothing to worry about our mutual approach to the Iranian issue. We have the same main objectives," Shapiro said, speaking in Hebrew. "Our leaders agree on those objectives. The main objective is to prevent Iran from obtaining a nuclear weapon."
It's likely Netanyahu will press Obama not to be too trusting of Iran, whose new president delivered a conciliatory speech at the United Nations and declared his readiness for new negotiations with the West. Rouhani also said his country was not seeking — nor could it produce — a nuclear weapon.
That does not square with Israel's position. Netanyahu was expected to bring intelligence with him to Washington that Iran was on the cusp of achieving the ability to produce a nuclear weapon. He has previously argued for action to block Iran from acquiring the tools to reach that threshold.
Zarif, a former nuclear negotiator for Iran, scoffed and said Israeli leaders have been warning that Tehran is months away from having a nuclear weapon since 1991, and those fears have never been realised.
"We're not six months, six years, 60 years away from nuclear weapons. We don't want nuclear weapons. We believe nuclear weapons are detrimental to our security," he said.
Iran has offered to open its nuclear facilities to international inspectors as part of broad negotiations with the United States but has insisted its nuclear program is its right and is for peaceful purposes only.
Eytan Gilboa, an expert on US-Israel relations at Israel's Bar-Ilan University, predicted a "very difficult conversation" between Obama and Netanyahu on Monday.
The Americans "like Rouhani," Gilboa said. "They think he represents a new policy, a new approach and therefore should be given at least a chance."
The Israeli prime minister is not convinced, Gilboa said. "Netanyahu's strategy is to say that this whole thing is a big hoax."