BY PULLING out of the Iran nuclear deal, President Donald Trump is counting on renegotiation or regime change. He is more likely to end up with war.

On May 8th Mr Trump did not cut America’s ties with the Iran deal so much as take an axe to it. The Joint Comprehensive Plan of Action, as it is known, curtails Iran’s nuclear programme for a number of years and permanently subjects it to intrusive inspections, in exchange for the lifting of sanctions. Mr Trump’s withdrawal from the “decaying and rotten” agreement honoured a campaign promise. However, the president was unexpectedly harsh in vowing to extend sanctions, not just restore them, and to punish any firm doing business with Iran wherever it is based.

Since the UN says that Iran was honouring the agreement, as even its critics allow, Mr Trump has strengthened the arguments of foes that America cannot be trusted and that the global rules it claims to uphold are made to be broken. The question for the other parties to the deal (Russia, China, Germany, Britain, France and the European Union) is: what next? The question for the world as a whole, especially the Middle East, is: what does this mean for Iran’s ability to get the bomb?

First tragedy, then Farsi

In Tuesday’s announcement Mr Trump offered his own answers. He said that he is “ready, willing and able” to negotiate a new deal that limits Iran’s regional aggression as well as its nuclear weapons, though he offered no plan for bringing that about. He also issued a veiled appeal to the Iranian people, who he said are being held “hostage” by their government, to rise up against their oppressors.

At its heart, Mr Trump’s plan is based on a hunch about sanctions. First it assumes that, with heavier sanctions, Iran’s economy will be less able to finance warfare in Iraq, Syria, Lebanon and Yemen. Yet Iran’s belligerence is not the outcome of a book-keeping exercise. Notwithstanding last year’s street protests, which called for more spending at home, Iran finances troops, militias and terrorists because it craves influence and it perceives threats. Mr Trump set out to intimidate Iran this week: he may have left it more determined.

Second, Mr Trump assumes that economic pain from new sanctions could force Iran to the negotiating table, as it did North Korea. Heavy sanctions can indeed lead regimes to negotiate, as Iran showed in the deal that Mr Trump has now rejected. But Mr Trump displays little sense of how the very leaders he has just welched on can surrender wholesale to his demands and survive.

Perhaps that is the point, and his real bet is that sanctions will bring about economic agonies that topple the regime. The mullahs will not rule Iran for ever. But the Castros in Cuba have withstood sanctions for decades. Iran’s theocrats have proved perfectly willing to keep order by force.

This newspaper would welcome an end to Iranian belligerence and to the regime itself, but a wish based on a hunch is not a policy. Instead, faced with the probable failure of Mr Trump’s scheme, the parties to the deal should strive to keep it alive for as long as they can. One aim is to demonstrate to Mr Trump and his supporters that global rules do matter. The EU should, for instance, continue to meet Iranian officials and protest to the World Trade Organisation about American sanctions on its companies, as it did 20 years ago when America applied secondary sanctions over Cuba. The other aim is to hold Iran back from restarting its nuclear-weapons programme.

Realistically, however, China and Russia may not want to dig Mr Trump out of the hole he has made for himself, and the EU cannot save the deal on its own. The dollar is still dominant (though Mr Trump has surely brought forward the day when China clears global payments in yuan). Companies with a choice between operating in America or Iran will inevitably choose the bigger market.

So the gains from a partial deal will be negligible and Iran may well sooner or later restart its nuclear programme. The Iran deal guarded against that, by providing an early warning and the option to reimpose sanctions. Without it, Iran may seek to return to the old limited inspections regime, to build new centrifuges, to enrich uranium to near weapons-grade and to miniaturise warheads. If the Iranian programme goes underground—literally and figuratively—there may not be enough intelligence to assess the threat. Moreover, with sanctions already ratcheted up high, Mr Trump and his successors will have limited diplomatic scope to get Iran to stop. Instead, they will have to resort to military action.

You do not go to war with Iran lightly—would Mr Trump fight over, say, some extra centrifuges? Iran would be able to creep towards the nuclear threshold. And, unlike the Iraqi and Syrian programmes, which were destroyed in one mission by the Israeli air force, Iran’s know-how and industrial capacity cannot be bombed out of existence. If Iran is determined to get a weapon, America or Israel will have to bomb it every few years. How would they justify that? It is hard to think of any previous American president tossing aside an international agreement for such poor odds and at such a heavy cost.