The Iran deal
An overview of the key points is here; basically, Iran will stop enriching uranium to near weapons grade, and its existing near-weapons-grade stockpile will be converted to oxide, making it unusable in bombs; Iran will also stop work at the Arak heavy-water reactor which could produce weapons-grade plutonium. In return, the US will provide about $6 billion in sanctions relief, mostly in the form of releasing frozen oil revenues.
On the critical issue of verification, most reports say little, but according to the New York Times:
To guard against cheating, international monitors would be allowed to visit the Natanz enrichment facility and the underground nuclear enrichment plant at Fordo on a daily basis to check the film from cameras installed there. But Iran did not agree to all of the intrusive inspection regime that the International Atomic Energy Agency had said was needed to ensure that the Iranian program is peaceful.
Of course, surveillance via espionage will presumably continue. The key question is whether we could catch the regime violating the agreement if they did so -- and we probably could, or at least they won't feel confident that we couldn't.
Not everyone is happy. Iran's main regional opponents, Israel and Saudi Arabia (how's that for strange bedfellows?) are signalling displeasure, and Republicans are displaying their usual stupidity. And caution is necessary. Nuclear weapons in the hands of Iran's current regime would be intolerably dangerous; all options to prevent this, including military ones, must remain on the table if it looks like the regime is trying to cheat.
But I think that's unlikely. Besides the US, parties to the deal include Russia, China, Germany, France, and Britain; no big power remains that could back the Iranian regime if it double-crosses us. Only 34% of Iranians support developing nuclear weapons, and initial reports suggest that yesterday's deal is very popular with the Iranian people, even regime supporters. Iran's new President Rouhani is described by people who have dealt with him as a patriot and a pragmatist; if so, he surely sees that relief from sanctions is much more in Iran's national interest than pressing on with a weapons program which would eventually provoke a devastating military attack.
Finally, we need to re-assess the Iranian popular uprising of 2009. This rebellion was generally judged a failure, despite its huge size -- the theocracy did not fall, nor did it moderate its internal repression. But the rising may have achieved a victory in the longer term. It was provoked by blatant election-rigging that year, but in this year's election (which brought Rouhani to power) the regime did not attempt such a scam again. Perhaps it didn't dare -- another massive uprising might have brought down the whole system. The people got their say, and Rouhani got a genuine mandate empowering him to stand up to the ayatollahs. And he had campaigned on a platform emphasizing reconciliation with the West. The 2009 rebellion may have been the trigger for a process of gradual change from within the regime. The real test, of course, will be whether the theocracy softens its brutal repression of the Iranian people.
Andrew Sullivan has a round-up of reactions to the nuclear deal.