President Barack Obama has assured Israel that the United States will always stand by it in a display of unity between allies who often disagree.
He told visiting prime minister Benjamin Netanyahu they agreed that diplomacy is the best way to resolve the crisis over potential Iranian nuclear weapons.
"Both the prime minister and I prefer to solve this diplomatically," Mr Obama said as he Mr Netanyahu began several hours of White House consultations. The US will consider all options in confronting what it sees as the unacceptable outcome of an Iranian bomb, Mr Obama said.
"Israel and America stand together," Mr Netanyahu said. He added that Israel is a sovereign nation with the right to defend itself, a pointed reference to the main question hanging over the high-stakes meeting: Whether to try to stop an Iranian bomb by with a military attack in the next several months.
Israel must remain "the master of its fate," he said.
Mr Obama will try to persuade him to slow pressure among many in his hawkish government to attack Iran's disputed nuclear development sites. Mr Obama is trying to avert an Israeli strike that could come this spring, and which the United States sees as dangerously premature.
The president is expected to tell Mr Netanyahu in private that although the US is committed to Israel's security it does not want to be dragged into another war. He is unlikely to spell out US "red lines" that would trigger a military response, despite Israeli pressure to do so.
Mr Obama previewed the White House meeting with a speech on Sunday to American supporters of Israel, a key constituency in this election year.
He said he does not want war but insists he would attack Iran if that was the only option left to stop that nation from getting a nuclear weapon.
"Loose talk of war" only plays into Iran's hands, Obama said.
US officials believe that while Tehran has the capability to build a nuclear weapon, it has not yet decided to do so. They want to give sanctions time to pressure Iran to give up any military nuclear ambitions. Israel says the threat is too great to wait and many officials there are advocating a pre-emptive strike.