Israeli Prime Minister Benjamin Netanyahu warned John Kerry Friday he was offering Iran the "deal of the century" as the US top diplomat headed to landmark talks in Geneva seeking a nuclear agreement.
Netanyahu vowed that Israel would not be bound by any international agreement on Iran's nuclear programme and reserved the right to do whatever is necessary to defend itself -- a clear allusion to a pre-emptive military strike.
Meeting with the US Secretary of State on the tarmac of Ben Gurion airport near Tel Aviv, the Israeli leader, a fierce opponent of any let-up in sanctions, lashed out at the world powers' cautious rapprochement with Iran and denounced the proposed agreement being hammered out in Switzerland.
Kerry flew in from Amman for a brief stopover in Tel Aviv and his third meeting with Netanyahu in as many days, in a bid to soothe Israeli anger ahead of his arrival in Geneva.
There he will hold a three-way meeting with Iranian Foreign Minister Mohammed Javad Zarif and EU foreign policy chief Catherine Ashton, who is chairing the talks.
"Iran got the deal of the century and the international community got a bad deal, this is a very bad deal. Israel utterly rejects it," Netanyahu told reporters.
"Israel is not obliged by this agreement and Israel will do everything it needs to defend itself and the security of its people."
Israel, which has the Middle East's sole if undeclared nuclear arsenal, staunchly opposes any easing of sanctions on a country whose leaders in the past have denied the Holocaust and said the Jewish state should cease to exist.
It views a nuclear-armed Iran as an existential threat and has consistently refused to rule out a pre-emptive military strike to prevent that from happening.
"I understand that the Iranians are walking around very satisfied in Geneva, as well they should be, because they got everything and paid nothing.
"They wanted relief of sanctions after years of a gruelling sanctions regime -- they got that -- they are paying nothing because they are not reducing in any way their nuclear enrichment capability," he said of the deal which has not yet been hammered out.
Washington has made clear that Kerry's arrival in Geneva does not signal that there is a done deal with Iran.
"In an effort to help narrow the differences in negotiations, Secretary Kerry will travel to Geneva, Switzerland today at the invitation of EU High Representative Ashton to hold a trilateral meeting with High Representative Ashton and Foreign Minister Zarif on the margins of the P5+1 negotiations," State Department spokeswoman Jen Psaki said in a statement.
Western governments -- and Israel -- suspect Iran of seeking to develop a nuclear weapons capability under cover of its civilian programme.
Tehran denies any such ambition and, since President Hassan Rouhani took office in August, has made overtures suggesting it is prepared to scale back its enrichment of uranium in return for the easing of crippling Western sanctions.
Washington, which has not had diplomatic relations with Iran for three decades, has repeatedly said it is going into the talks with eyes wide open, seeking to explore the diplomatic possibilities of bringing its suspect nuclear programme under international control.
A senior State Department official said that since the first round of talks with the Rouhani administration last month, Kerry has been open to the possibility of travelling to Geneva for this current round if it would "help narrow differences."
Ashton had asked Kerry to attend the second day of talks for that very reason, the official added.
"As we've said, this is a complex process. And as a member of the P5+1, he is committed to doing anything he can to help," he said.
Iran's Zarif was to meet early Friday with Ashton, who is chairing the talks on behalf of the P5+1 -- which groups UN Security Council permanent members Britain, China, France, Russia and the United States, with Germany.
So far, Western officials have described the current talks as "substantive" and "productive."
"There is a window of opportunity now that has been created by the Iranian people... and that opportunity needs to be seized," Zarif said after the first day of talks on Thursday.
Iran is anxious for relief from crippling Western economic sanctions that have cut oil revenues by more than half, caused the value of the rial to plunge and pushed inflation above 40 percent.
The West is also keen to seize a rare opportunity to build bridges with Iran after decades of hostility, opening the door to engaging with Tehran on other issues like the conflict in Syria, where Iran has backed President Bashar al-Assad against insurgents.