The Iranian nuclear deal reached in Switzerland on Thursday is a significant breakthrough. Uncertainties remain, inherently so, as it’s merely a “political framework” for a formal deal to be completed and signed by June 30. But this framework turns out to be far more detailed, quantitative, and restrictive than anyone had expected.

It might not lead to a deal as good as the outline suggests; it might not lead to a deal at all. But anyone who denounces this framework—anyone who argues that we should pull out of the talks, impose more sanctions, or bomb Iran because it’s better to have no deal than to have this one—is not a serious person or is pursuing a parochial agenda.

If this deal is fully implemented, Iran will be unable to build a nuclear bomb by enriching uranium or by reprocessing plutonium for at least 10 years. Some of the restrictions imposed by this deal would last 15 years. The international inspections of certain aspects of Iran’s nuclear program would stay in place for 25 years.

As for the economic sanctions against Iran, they would be lifted not upon the deal’s signing, as the Iranians initially demanded, but only after the inspectors have verified that Iran has fulfilled all of its commitments in the deal.

These commitments include reducing the number of Iran’s installed centrifuges by two-thirds (from about 19,000 to 6,104, with only 5,060 allowed to enrich uranium); reducing its stockpile of enriched uranium by 97 percent (from 10,000 kilograms to 300 kilograms); to remove all advanced centrifuges (those that can enrich uranium at a much faster rate) and to place them in internationally monitored storage; to destroy the core of the Arak heavy-water reactor (which could produce a plutonium bomb), ship all its spent fuel out of the country, and forgo additional reprocessing; among other things.

If the Iranians honor these terms, they will not be able to build a bomb for at least a decade, maybe longer. Still, there are two questions that a final deal would have to answer concretely.

First, it’s not clear when the sanctions would be lifted. An official summary of the framework states, at one point, “Iran will receive sanctions relief, if it verifiably abides by its commitments.” Elsewhere, it says that all U.N. Security Council resolutions on Iran nuclear issues “will be lifted simultaneous with the completion, by Iran, of nuclear-related actions addressing all key concerns.”

But this leaves open the question of timing. Some of these “commitments” are to be carried out through the duration of the deal, yet certainly there’s no suggestion that the sanctions will remain in place for a decade. Are the relevant commitments those that involve the reduction or dismantlement of nuclear equipment? If so, will the sanctions be lifted in phases or all at once when the cuts and shutdowns are complete?

The framework also states that sanctions can be “snapped back” into place if, at any point, Iran violates any part of the deal. But as everyone knows, it’s much harder to reimpose sanctions than it is to lift them, especially at the U.N. Security Council, where Russia and China (which signed on to the sanctions reluctantly and want to see them lifted as soon as possible) have veto power. So everything else about this deal has to be solid.

(However, it’s worth noting, the framework states that sanctions relating to Iran’s ballistic missiles, violations of human rights, and support of terrorism will still be in place. So if the nuclear sanctions do need to be “snapped back,” they could be piled on top of these sanctions; a mechanism for freezing funds would still exist.)

Second, the deal would have to let international inspectors not only monitor Iranian nuclear facilities continuously, but also to look inside any other “suspect” facilities—in other words, facilities not on the official list that the inspectors have reason to believe might be harboring prohibited activity. Verification has been the most nettlesome aspect of all arms control accords throughout history, for two reasons. First, no deal can be absolutely verifiable; this is why accords usually set a standard of “adequately verifiable” (a bit of a finesse, but there’s no honest alternative). Second, even in the most trusted relations (and relations with Iran are far from that), there is a fine line between authorized inspection and disingenuous espionage—which is to say that Iran (or any other military power) might have understandable, even legitimate reasons for wanting to keep foreigners out of certain areas.

So why should the P5+1 nations—the five permanent members of the U.N. Security Council (the United States, Great Britain, France, Russia, and China) plus Germany—pursue this deal, despite the uncertainties?

The main reason is that it is a profoundly good deal; there has never been a nuclear deal, with any country, that is so comprehensively restrictive. Israeli Prime Minister Benjamin Netanyahu urged the U.S. Congress to demand “a better deal,” but his definition of such a deal—one that bans uranium enrichment, dismantles all its facilities, and insists on a drastic change in Iran’s foreign policy—is unattainable, and, more to the point, he knows it.

Yes, this deal wouldn’t keep Iran from being a menace in Middle East politics, or from repressing its own people. But no arms control deal can aspire to do that. The U.S.-Soviet strategic arms treaties, signed throughout the Cold War, didn’t require the Soviet Union to disavow communism, end its support of Third World insurgencies, or institute Jeffersonian democracy—but the deals were still very useful. They capped, and in the later years reversed, the nuclear arms race; and they provided a forum for diplomacy, a cooling-off of the distrust and hatred, at a time when no other issues could have done so.

In his speech to Congress, Netanyahu condemned the deal—long before its outlines were set—because it paved the way for a nuclear Iran a decade hence, noting that 10 years is like the blink of an eye in the annals of nations. First, many things can happen in 10 years. (Among other things, most of Iran’s mullah rulers will probably have died.) Second, would he rather pave the way for a nuclear Iran in the next six months?

Netanyahu’s unlikely allies in opposing the deal—the rulers of Saudi Arabia, Egypt, and other Sunni Muslim oligarchies—simply don’t want a deal at all. They fear above all an ascendant Shiite Iran, especially an Iran enriched by the flow of money that comes with the end of sanctions and the resumption of global investment and trade. They would, in fact, prefer an Iran that aspires to build nuclear weapons—an Iran that blatantly looks like a threat—to an Iran that might be stalled in the nuclear realm (and thus might seem more peaceful) but in fact still pursues its expansionist aims.

This fear is understandable, from their point of view, but the United States shouldn’t adopt the Sunnis’ perspective—shouldn’t get drawn into their war with the Shiites—if it means forgoing the opportunity of a truly historic, potentially transformative deal. Even from the Sunnis’ point of view, which would they prefer: an expansionist Iran with nuclear weapons or without?

They’re right, the end of sanctions could make Iran more powerful; but the international community has held firm on the sanctions for as long as they have only because they’ve been seen as the lever for a deal. If the deal collapses, and if the United States is held responsible for the failure, the sanctions would collapse as well.

Which leads to another reason for continuing these talks: If there is any chance that Iran might modify its stance over the next decade or so, might even become a “normal” nation, these talks might usher in this change. Tehran’s rulers have long justified their alliance with terrorists and their repressive domestic policies by raising alarms about the threat from demonic America. If the Iranian people see their own leaders meeting and smiling with American diplomats, even negotiating deals, trusting them enough to dismantle huge pieces of the nation’s cherished nuclear program, then the chants of “Down with America” might soon lose their potency—and the regime’s political legitimacy, the rationale for its existence, could gradually evaporate.

But even if there is no regime change, this deal is far better than no deal, and there is no deal on the table but this one, and it’s a lot better than anyone would have predicted just a few days ago.