This is the shifting tectonic plate in the Middle East.
This is the giant story of the past few weeks which the world has largely missed, distracted by the theatre of the absurd of Obama's contrived and mock confrontation with Israel over 1600 apartments to be built in three years' time in a Jewish suburb in East Jerusalem.
Iran is the only semi-intelligible explanation for Obama's bizarre over-reaction against the Israelis.
In the Middle East, today, Iran is the story. It is the consideration behind all other considerations.
Obama has not explicitly announced his new position and he and his cabinet secretaries still make speeches saying they will try to prevent Iran acquiring nuclear weapons. But if you look at the statements closely you see a steady weakening of resolve, a steady removal of any threat of any consequence for Iran. Similarly, if you look at the actions of the administration, the sombre conclusion is inescapable.
Given Iran's missile program, which has no conceivable military use except to carry nuclear weapons, and which can now reach Europe and in due course will have a longer range, the fundamental change in US policy has global security consequences.
It has global security consequences in other ways, as well. It profoundly undermines American strategic credibility, which is the bedrock of whatever global order this troubled planet enjoys.
The troubling realisation that the Americans have given up, or are in the process of giving up, the fight to prevent Iran going nuclear is backed by the best informed security sources in Washington, London, Jerusalem and Canberra.
The bust-up between Washington and Israel only makes sense in this context. Last week, Israel's Prime Minister Benjamin Netanyahu met Obama in the White House, and also met Secretary of State Hillary Clinton at the State Department. On both occasions, all photographers and all TV cameras were banned. This was a studied humiliation of Netanyahu and all, ostensibly, because Israel announced that in three years' time 1600 apartments would be built in a Jewish neighbourhood in East Jerusalem. Yet the 10-month moratorium on new residential building in the West Bank which Netanyahu had announced in October to effusive US praise had specifically exempted East Jerusalem.
It is inconceivable that Obama would have treated any Arab or Muslim leader with the same considered contempt that he showed to Netanyahu. I speculated last week that Obama engaged in his furious over-reaction in order to pursue personal popularity in the Muslim world, and perhaps to force Israel to make so many concessions that the Palestinians would come back to negotiations. Although these negotiations would not produce a comprehensive peace deal, at least Obama could claim the talks themselves as a victory of sorts.
I still think these were important considerations but there was a much bigger strategic purpose, as well. In 2008, Israel told Washington it was planning to strike Iran's nuclear facilities. Washington talked Jerusalem out of the move, not least by showing its own determination to stop the Iranians.
In those days, senior Americans from then-president George W. Bush down, often said that "all options are on the table" in their determination to stop Iran acquiring nukes. All options explicitly included an American military strike on Iran's nuclear facilities. When Obama spoke to the American Israel Public Affairs Committee in 2008, he said he would use "all elements of American power to pressure Iran".
He won a tumultuous standing ovation by using a repetition of a key word to emphasise his determination. He said: "I will do everything in my power to prevent Iran from obtaining a nuclear weapon - everything in my power to prevent Iran from obtaining a nuclear weapon - everything." That was Obama's equivalent to Bush's "all options".
Obama doesn't talk anything like that any more. In his message to Iran on the Iranian new year a few weeks ago, he reiterated his determination not to meddle in Iran's internal affairs and said the nuclear matter should still be negotiated.
Clinton, in her address to the American Israel Public Affairs Committee last week, spoke only briefly about Iran, repeating a pro-forma US determination to stop it going nuclear. But there was no mention of all options, everything the US could do, or all aspects of US power. Instead, she said that while sanctions were taking a long time to work out at the UN, it was time well spent, and they would show Iran that its actions had consequences.
But the bulk of her speech was all about the Israeli-Palestinian issue.
Presidential and Secretary of State speeches on subjects like this are given a level of attention that wouldn't be out of place in the preparation of a papal encyclical. The sub-text of Obama and Clinton's recent speeches can only be that they have decided that the battle against a nuclear-armed Iran is over.
One thing they are determined to do is to stop Israel from taking its own unilateral military action to stop or retard Iran's nuclear program. Israel has taken this type of action twice before. In 1981, it destroyed Iraq's nuclear reactor at Osirak. And in 2007, it bombed into obliteration a North Korean-supplied secret nuclear reactor in Syria.
It is impossible to know with absolute certainty what Israel's intentions were, or are, for the Iranian nuclear program. But for several years the most senior US officials would agree that a nuclear-armed Iran represented an existential threat to Israel. Iran's rulers, after all, not only deny the Holocaust but have made militant anti-Americanism, confrontation with Israel and even anti-Semitism, defining ideologies of the Iranian state. Iran's President, Mahmoud Ahmadinejad, has threatened to wipe Israel off the map. Most analysts believe that for all their extremism, the Iranian rulers are rational actors and would not actually use nuclear weapons. But this is a slender analytical thread to ask Israelis to hang their very lives on. And the danger of Iran proliferating some element of nuclear material or technology to terrorists is much more plausible.
This is where the Obama-Israel dust-up comes in. By so isolating Israel, by irresponsibly unleashing a global wave of anti-Israel sentiment, especially in nations which normally support Israel, Obama has made the possibility of Israel considering unilateral action against Iran much more unlikely. The Israelis would weigh such action very carefully. There are many pluses and minuses. By creating the impression of Israel as a besieged, isolated and reckless nation, which the wildly disproportionate reaction to the East Jerusalem apartments accomplished, Obama has made the potential cost to Israel of action against Iran much greater.
Is it fair to conclude definitively that Obama has decided to give up, except for symbolic and meaningless actions, the fight against a nuclear-armed Iran?
Obama might still change his mind - he is nothing, after all, if not flexible - but that is the inescapable conclusion of his actions so far.
He has set so many deadlines for Iran. Each of them has passed and nothing ever happens. There are never bad consequences for the US's enemies in Obama world, it seems, only for its friends.
Remember, initially, that the Obama administration wanted to wait for the Iranian election in the middle of last year before it exhausted dialogue or went down the sanctions road? Remember then the deadline was September? Remember the proposal for Iran's uranium to go to Russia for enrichment? Remember the revelation of Iran's secret nuclear facility at Qom? Remember Iran's announcement that it intended to enrich uranium up to 20 per cent, a vast leap on the technological road to weapons? Did you notice a couple of weeks ago Iran's announcement that it would build new nuclear facilities?
And where are we today? Now it is April and Obama is still talking in his feckless way about possible UN sanctions. Anything that is passed by China and Russia at the UN Security Council will be weak and ineffective. A serious US administration would have built a critical mass of like-minded countries to impose crippling sanctions on Iran outside the Security Council.
The only explanation that fits with all the facts is that the US administration is no longer serious about stopping Iran from getting nuclear weapons. James Lindsay and Ray Takeyh, writing in this month's Foreign Affairs, declare that: "If Iran's nuclear program continues to progress at its current rate, Tehran could have the nuclear material needed to build a bomb before US President Barack Obama's current term in office expires." The Foreign Affairs article, After Iran Gets the Bomb, is important in another way. It demonstrates the drift in the serious discussion in the US. It is no longer a discussion of how to stop Iran getting the bomb, but how to cope with a nuclear-armed Iran.
Here's something else you should know about Iran. US General David Petraeus, in written testimony to congress, has revealed that Iran is co-operating with al-Qa'ida in Afghanistan and Pakistan, facilitating the movement of its leaders. The Sunday Times of London recently carried interviews with Taliban leaders who were trained in Iran.
There is no chance Obama will produce a comprehensive Israeli-Palestinian peace deal in his first term in office, which is how he would like to be remembered by history. There is every chance history will remember him for something altogether different, as the American president on whose watch Iran became a nuclear-weapons state.