Robert Jenrick was Secretary of State for Housing, Communities and Local Government, and is MP for Newark.

The news of the release of Anoosheh Ashoori and Nazanin Zaghari-Ratcliffe from Iran was a ray of light in the dark clouds we’re living under. The scenes of Nazanin being reunited with her family at Brize Norton moved the nation, who have taken the Zaghari-Ratcliffe family into their hearts and followed every step of her journey.

We can only marvel at the determination and resilience these families have displayed. Through these most complex of negotiations, Boris Johnson and Liz Truss have got them home.

Some have dwelt on whether there was anyway we could have responded to their detention differently. But we mustn’t lose sight of the fact that the responsibility for this ordeal lies solely with Tehran.

It was Iran that detained our nationals, Iran that subjected them to this inhumanity and Iran that used them as pawns in the settlement of an historic debt or payment of a ransom. Nazanin and Anoosheh’s torment is just one example of the despotism of a regime who cling to power by starving millions of Iranians of their most basic human rights.

And the brutality of the Iranian regime extends far beyond its borders. It has sowed chaos in Syria and Yemen, encircled Israel with proxy forces and in recent years turned its missile attacks on Saudi Arabia and the UAE. Tehran’s belligerence has created previously unimaginable coalitions in the region in a desperate attempt to balance against Iran’s hegemonic ambitions.

Whilst it may seem a distant power, Iran poses a clear threat to our security here in the UK. Its financial and military support for international terror groups gives it reach far beyond the Middle East.

It barely registered here in Britain, but it was only a last-minute intervention by the French intelligence services in 2018 that foiled a bomb plot by an Iranian diplomat at an opposition rally in France, attended by several parliamentary colleagues. The prospect of a nuclear Iran would be destabilising for the UK, and that is before the proliferation effects are even considered.

So, whilst the focus of the West rightly remains on Ukraine, the progress of talks in Vienna to return Iran to the JCPOA nuclear deal deserves our attention.

Last week it appeared that a deal to return Iran to the agreement was imminent, but Russia’s eleventh-hour demand that sanctions relating to its invasion of Ukraine could not affect its trade with Iran have led to a pause.

Russia has been playing a key role in this process, at times acting as broker between the US and Iran – to the increasing astonishment of many observers in the US – as Putin seeks to use the negotiations to gain political prestige and leverage.

This break in the process offers a precious final opportunity to evaluate the merits of such a deal. I was a sceptic of the original 2015, seeing it, like many (Conservatives and Republicans in particular) as too limited in scope to prevent Iran’s malign activities and too weak in enforcement to prevent a nuclear Iran, should Iran choose that path.

Restoring Iran to the old deal simply won’t have the benefits it once did. In the seven years since the deal was agreed much has changed. The terms of the JCPOA restricted Iran’s enrichment of uranium to 3.67 per cent fissile purity and a stockpile of only 300kg of uranium; however, as of last month the IAEA confirmed that Iran’s declared stockpile stood at nearly 3,400kg and it has been enriching up to 60 per cent purity – a short technical step from weapons-grade levels of 90 percent.

Whilst the excess uranium can be removed, Iran’s development and installation of advanced nuclear centrifuges cannot simply be unlearned. Their nuclear programme has clearly made substantial progress and yet, under the terms of the deal currently being negotiated in Vienna, restrictions on Iran’s nuclear programme are now severely diminished because the sunset clauses have not been extended.

All the while the same structural problems with the 2015 deal remain. The deal appears to do nothing to rectify the issue of Iran blocking international inspectors’ access to nuclear sites to ensure that Iran is complying with the deal, with the recent discovery of uranium particles at undeclared facilities casting yet more doubt on the trustworthiness of the Iranian regime to comply with their obligations.

More broadly, this will do nothing to stall Iran’s rapidly progressing ballistic missile programme, destabilising activity in the region, or funding of terrorist proxies.

In fact, it is being suggested that the Biden administration will lift sanctions on proscribed terrorist groups, most concerningly the Islamic Revolutionary Guard Corps (IRGC), who have just claimed an attack on a US diplomatic compound in Erbil. The IRGC has been linked to the killing and detention of British and American citizens and spreads terror around the world, supporting organisations such as Hamas and Hezbollah.

These are the very groups which the Home Secretary has recently, rightly, proscribed in the UK. It would therefore be surprising, to say the least, if we or our allies were to consider lifting sanctions on the IRGC.

Negotiations in Vienna cannot be detached from the broader geopolitical landscape. As the West pressures Putin to engage in serious negotiations through a package of crippling economic sanctions, high oil and gas prices have proved a lifeline for his war efforts.

For some, this has created an added incentive to reach a deal with Iran, on the basis that this would release a much-needed supply of oil into the market.

However, Saudi Arabia and the UAE are the two states with the capacity to significantly lower global oil prices. It was, after all, the decision by Saudi Arabia to crash the oil price in 1986 that began the Soviet Union’s collapse. For an economy whose finances were so reliant on high oil prices, the effects on the Soviet Unions were crippling.

Today, an estimated 36 per cent of the Russian budget is made up by oil and gas revenues (a figure likely higher given the paralysing effect of sanctions on the rest of the economy) which would make a drop in the global oil price just as costly. If the Gulf states flooded the market with oil, this would tighten the screw on Putin.

But the prospect of a weak deal with Iran currently stands as a major sticking point. We risk facing the worst of all words, where Iran is emboldened at the expense of our partners in the region, and we also lose the ability to bring the Gulf states onside in the battle against Putin – the central short term objective of our foreign policy.

The West may have underestimated its strength in these negotiations. Since 2018 the Iranian economy has been crippled by America’s financial might. The latest estimate suggests a deal would free up $90 billion in foreign exchange reserves, and then $50-55 billion in extra revenue each year from higher petrochemical exports.

This is a transformative amount of money for the Iranian regime and should only be granted in return for credible protections against Iran’s nuclear programme and its malign regional activities that can reassure Iran’s neighbours.

But the concern that the West is giving away too much sanctions relief for what it is receiving in return has already led to three US negotiators to resign. There is a suspicion that the Biden administration, having suffered a serious foreign policy setback in Afghanistan, may be too eager to agree terms in this case, in order to display progress on another front.

Scepticism of the deal has united the Republicans and Democrats on an issue which has hitherto remained polarised along party lines, with 70 Democrats and 70 Republican lawmakers writing to Anthony Blinken last week to outline their concerns.

Without bipartisan support behind the deal – which ultimately means toughening its bite – there is a very real risk the deal will be canned by the next administration. If this deal fails there will be no third chance.

For the British negotiating team, this means using our influence to stiffen the resolve of our friends across the pond. If the new deal is to achieve anything, a tougher stance is required. We’ve learnt with Putin that placating can feel good, until it fails – and it usually does.