Both the US and Israel want to curb Iran's nuclear programme and prevent it from having the resources to build a nuclear weapon, but the two countries have clashed over what Iran should have to agree to.
While the US wants it to freeze its nuclear programme for a decade, Israel does not believe this concession goes far enough, arguing that a nuclear-armed Iran would pose an existential threat to the Jewish state.
Major world powers have imposed sanctions on Iran until it eases its nuclear enrichment activities, and talks have been held to try and reach an agreement. The 31 March deadline for a framework deal is fast approaching, with a final agreement needed by 30 June.
During an interview at the White House yesterday, US President Barack Obama said there was a “substantial disagreement” between him and Israeli Prime Minister Benjamin Netanyahu over what that deal should involve.
But why do the two allies disagree so much on how to achieve their shared goal?
What the US says
One of Obama's main arguments for trying to get Iran to agree to a freeze is that it is better than other options – the continuation of sanctions and military action. “It would be far more effective in controlling their nuclear program than any military action we could take, any military action Israel could take and far more effective than sanctions will be,” he said.
He also believes it will ensure there is “at least a year” between Iran trying to get hold of a nuclear weapon and actually using one – a time period the US leader views as critical for putting the breaks on Iran.
As evidence that Israel might be wrong in its objection to the proposed deal, he cited the success of his 2013 interim deal with Iran, which Netanyahu also opposed.
"Netanyahu made all sorts of claims. This was going to be a terrible deal. This was going to result in Iran getting 50 billion dollars worth of relief. Iran would not abide by the agreement. None of that has come true,” he said.
"It has turned out that during this period we’ve seen Iran not advance its program. In many ways, it’s rolled back elements of its program.”
What Israel says
During a speech in Washington yesterday, Netanyahu argued that Obama was being too diplomatic in his dealings with Iran, and that the proposed deal would not stop the development of an atomic bomb.
“I have a moral obligation to speak up in the face of these dangers while there is still time to avert them,” he said to thousands of Jewish supporters.
He said it was as though negotiators had given up on their pledge to prevent Iran from acquiring nuclear weapons, and that this threatened the existence of Israel.
Despite believing his deal is the best way forward, Obama still thinks it is unlikely that Iran will agree to it before the deadline – he said they would most likely have a problem with the rigorous inspection demands and requirement for low levels of uranium enrichment capability.
"I would say that it is probably still more likely than not that Iran doesn’t get to 'yes,'” he said. But he added their chance of agreeing now is higher than it was five months ago.
Tehran denies that it is trying to develop nuclear weapons.