The moment that, in his Aipac speech on Sunday, President Obama began reeling off all the instances over the past three years when his administration had stood firmly by Israel, Prime Minister Benjamin Netanyahu's advisers went into crisis mode.
If the President needs, in a speech to the pro-Israel lobby, in an election year, to cite his past support in such detail, it can only mean one thing.
He is about to let Israel down badly.
President Obama has not changed his position on a military strike against Iran. But in three separate high-profile opportunities this week, he made sure that Mr Netanyahu understood there were two components to US policy.
Instead of sticking to the old formula of "all options are on the table", the President made it clear that as commander-in-chief he was indeed prepared to send American soldiers into harm's way if there was no other option to preventing Iran from achieving a nuclear weapon.
His defence secretary, Leon Panetta, reinforced that message.
But with even greater vigour, President Obama highlighted the undesirability of another Middle East war and made it clear that diplomacy and sanctions still have a long way to go.
In one of his appearances, the President even said that it would be "months" before a decision on military action needed to be made. Without directly mentioning the Israeli Prime Minister, he excoriated "loose talk of war" and chided his Republican rivals for treating war with Iran as "a game."
While Mr Netanyahu and President Obama were careful to keep their differences below the surface and remained cordial, at least in public, the differences in tone and content between the two leaders was clear, not least when, in his words to the media in the Oval Office, the Israeli Prime Minister failed to mention the President's much preferred diplomacy even once.
But if both men simply dug deeper into their well-established positions, what was the point of this month meeting between them?
President Obama's team hope that they have managed to impress on the Israelis their reasons for not jumping into another war, though they say privately that they are not very hopeful.
Mr Netanyahu's aides take a very different tack. Three years ago, when the two newly-elected leaders first met, President Obama wanted to focus on the Palestinian issue, while Mr Netanyahu insisted that Iran was the real story.
This time around the Palestinians didn't even get a look-in. Proof, perhaps, that Bibi has prevailed.