What was the most important thing to happen in the world in the last 50 years or so? There’s a case to be made that it was the Iranian revolution of 1979, a violent and unexpected swerve from which the world has yet to recover.

It is hard to remember back when Iran was America’s closest ally in the Middle East (and the US government was helping Iran build nuclear reactors for the peaceful use of atomic energy.) But the change of Iran from US’s fast friend to its fierce foe set in motion a chain of events that include the Soviet invasion of Afghanistan, the Israeli invasion of Lebanon, the rise of Al Queda, the rise of Hizbullah, the Iran-Iraq War, the first Gulf War, 9/11, the US Wars in Iraq and Afghanistan, the Arab Spring and its failures, the collapse of Syria, the war in Yemen, and a major reason for the lack of progress in Israel Palestinian peace efforts, and starting with the election of Ronald Reagan, a major boon to the success of right-wing politicians worldwide.

And the biggest change in Iran, since 1979, just might be the preliminary accord announced today between P5 +1 and Iran on curtailing Iran’s nuclear program. The preliminary agreement seems to be more detailed and specific, with more concessions to the West, than anyone thought possible. For whatever reason, and one can think of many, the Iranian leadership badly wanted a deal. There are many roadblocks on the way to its implementation, but only those who want another war in the Middle East (in addition to the 5 or 6 currently being waged) should be disappointed.

Obama, I suspect has been thinking of Nixon going to China. It’s hard to triangulate a foreign policy when you only have two sides of a triangle, and the war of Iraq and Syria have exposed the folly of relying on Sunni dictatorships (with Israel as a backup) as the US’s main allies in the Middle East without having an effective way to deal and speak to Shi’ites.

And of course the Republicans will not care what the agreement says, and the Israeli government will do the same. Both will do all in their power to undermine the agreement. I don’t think it will work. Although I don’t think that an Iranian nuclear weapons program would have been the existential threat to Israel than some imagine, I have no doubt that it would have further destabilized a region and led to a nuclear arms race. And most people will be happy to put that genie back in the bottle. I suspect that the Republicans will find that Americans really don’t want to go to war with Iran, and if the deal seems plausible, most Americans, with varying degrees of skepticism, will go along, and Boehner and company will be reduced to more pettifoggery over the Affordable Care Act, and trying to fan the dying embers of anti-gay prejudice in Indiana and elsewhere.

As for Netanyahu, a successful deal will remove one more excuse not to seriously deal with the Palestinian question. No one knows how this agreement will change the Middle East, but this is the first development of consequence in a long, long time that holds out the possibility of changing the region for the better.