FOR over three decades Iran and America have been blood enemies. Their hatred, like the hatred between the Palestinians and the Israelis, has framed the Middle East’s alliances and fuelled terror and war. The interim deal over Iran’s nuclear programme has not undone that—far from it. But through the keyhole it offers a tantalising glimpse of a different, better Middle East. It is a vision worth striving for.

Iran and six world powers, led by America, struck the six-month interim nuclear agreement in the early hours of November 24th (see article). Iran will cap its programme at more or less its capacity today, while the rest of the world will relax sanctions a little. But the deal matters mostly for what it heralds. If Iran shows restraint and the world rewards it, the negotiators might generate sufficient goodwill to reach a more durable and comprehensive agreement. And that would open up the possibility of America and Iran co-operating more, or at least feuding less, in the world’s most troubled region.

Bolts, but not nuts

Pure fantasy, say the Gulf Arab states and Israel (and its allies in Congress). Invoking Neville Chamberlain in Munich in 1938, they warn that the world is appeasing an aggressive and malign regime bent on a nuclear arsenal. During years of talks, Iran has earned a reputation for double-dealing. It is a sponsor of terror, Bashar Assad’s main backer in Syria and a mortal threat to Israel. The regime foments hatred of the Great Satan in Washington not by chance, but to justify its hold on power.

The deal is thus a lousy one, argues Israel’s hawkish prime minister, Binyamin Netanyahu, because Iran will never honour it or negotiate a final agreement. America has rewarded a wicked regime at the expense of its allies. A tough line—sanctions and talk of an Israeli attack—brought Iran to the table; only a tougher one will get it to give up its programme.

This newspaper sees it differently—in terms of both the risks and the rewards. Doing anything with Iran is a gamble, but in the short term there is not much for the West to lose. The big face-saving concession for Iran is that the regime is still permitted to continue enriching uranium. But the enrichment will be only to the 5% civilian level, and Iran has agreed to daily inspections of its nuclear facilities, to monitoring by cameras and to opening up more of its sites. If the regime makes a dash for a bomb, the world can find out soon enough to take action. If the talks break down, Iran will not be much closer to having a bomb than it is today—and further away than it would have been without a deal.

And the pressure is still on the regime. If Iran cheats or cynically sabotages further talks, it will embarrass Russia and China, which have staked their credibility on the agreement; they might back more sanctions. Barack Obama has rightly retained the threat of military action if Iran goes back on its pledge not to acquire a bomb. By contrast there is much to gain from sticking to the deal and going further—not least for Iran itself. Although it has already won about $7 billion of sanctions relief, the remaining oil sanctions alone will cost it about $30 billion in the next six months, a big incentive to move on to a bigger deal.

Whether it chooses to depends on Iran’s willingness to put its past as a pariah state behind it. It is here that the really big rewards begin. If ever there was a moment to test the idea that Iran is ready to change, it is now. The president, Hassan Rohani, was elected this summer on a wave of popular discontent towards the conservative establishment and the hardline policies of his predecessor, Mahmoud Ahmadinejad. Young Iranians are disenchanted. The supreme leader, though a sworn enemy of America, has given Mr Rohani licence to talk to the West. Were Mr Rohani to conclude that the regime had more to gain from being part of the world rather than wholly against it, that would be a prize in itself. But even larger rewards would come if a less isolated Iran became more reasonable, too.

Small chance, great prize

Iran is a country 77m-strong with a rich imperial history: it is also the most important Shia Muslim power. If it changes its outlook, the whole of the Middle East will change with it. Imagine that Iran one day concluded that spreading mayhem ultimately tends to create trouble at home and began to view its neighbours in terms of opportunities rather than threats. That would do more for the security of Israel and Saudi Arabia than any number of weapons agreements.

The immediate test, and opportunity, will be Syria. Without Iran, Mr Assad would have been ousted long ago. Now Iran is losing men and money there. It also shares, with America, a fear of the Sunni extremism flourishing in rebel-held areas. The West needs to accept that Iran must be at the table in the peace talks due in Geneva. If anybody can bully Mr Assad to offer concessions, it is Mr Rohani. And if Syria becomes even mildly more tranquil, it would calm its neighbours.

In Lebanon, suppose that Iran ceases using Hizbullah, its proxy, as a constant threat to the country’s stability and to Israel. Or that Iran started to use its influence over the Shia population in Iraq to broker peace, rather than to sow discord. Even if Iran merely started to be less mischievous in Iraq (or for that matter in Bahrain, Palestine and Yemen), the Middle East would become a more stable place. All this would take time—after 34 years America and Iran have a lot of catching up to do. But it is worth remembering that they were once allies.

Saudi Arabia and Israel are at once troubled by the prospect of a redeemed Iran and also convinced that the whole idea is a dangerous illusion. Yet the real fantasy is to imagine that more sanctions or harsher negotiations could have produced a deal that was much better than this one. The alternative was not for Iran to abandon its nuclear programme, but for America to abandon diplomacy—and prepare for an assault.

Bombing would probably set Iran back by only a few years; but it would certainly remake the Middle East in a very different way. Nobody knows whether the gamble with Iran will pay off. But it is already clear that the risks are low, the prize is potentially vast—and the alternative is dire.