Throughout, Iran would be subject to one of the most robust and intrusive inspection regimes in the world, with continuous video monitoring of its uranium mines for the next 25 years and monitoring of centrifuge production facilities for 20 years. Expanded inspections under the Additional Protocol are permanent.

As 30 nonproliferation experts attested to in a statement in April, “the agreement reduces the likelihood of destabilizing nuclear weapons competition in the Middle East, and strengthens global efforts to prevent proliferation, including the Nuclear Nonproliferation Treaty.”

Under the deal, Iran’s breakout time — the amount of time it would take to produce one bombs‐​worth of highly enriched uranium if it decided to do so — would be extended to roughly one year, up from roughly three months at the interim agreement’s inception.

To review these technical parameters and feverishly warn that the deal “paves the way for a nuclear Iran,” as Sen. David Perdue, R‐​Georgia, and others recently have is bizarre. Similarly, to declare as Sen. Marco Rubio, R‐​Florida, recently did that the deal would produce “a cascade of proliferation” in the region relies on an array of interlocking dubious assumptions.

What these wildly divergent assessments seem to indicate is that the sides were arguing over different problems. For the arms control community, the problem was an Iranian nuclear weapons capability. For them, given the one‐​two punch of political reality and the terms of the agreement, the deal was a good thing. It significantly reduced the probability of an Iranian nuclear weapon and could meet both sides’ minimum standard of necessity.

For neoconservatives and interventionist Democrats, the nuclear program was but one piece of a much larger problem: a looming Persian menace that threatened to dominate the Middle East. This explains the specious nonproliferation arguments offered in opposition to the deal, as well as the increased warnings of Iranian “regional hegemony” heard in the run‐​up to the deal.

These sorts of arguments are tendentious in the extreme, because on their own terms they fall short. The nuclear agreement is indeed helpful from the point of view of nonproliferation, and Iran has no path to regional hegemony in the policy‐​relevant future. Instead, these claims seem to be part of a larger strategy under which everything that happens tied to Iran is treated as a threat.

But the question in the context of nuclear diplomacy was never a choice between a neutered, Israel‐​recognizing liberal Iran or an empowered nuclear theocracy. It was between a nasty but weak regional power with little power‐​projection capability, closer or further away from a nuclear weapons capability. And on these terms, the agreement must be viewed as a clear success.