The transatlantic chasm on Iran policy has rarely been starker. Yesterday’s announcement from President Donald Trump to reinstate sanctions on Iran, effectively tearing up the Joint Comprehensive Plan of Action (JCPOA), sent gilt yields spiking and the pound dipping against the dollar. Meanwhile, former President Barack Obama's team issued a thinly veiled critique, defending the 2015 deal as a pillar of non-proliferation. For a British financial editor who has watched three decades of geopolitical risk, this is not merely a foreign policy squabble. It is a referendum on market stability and the cost of diplomatic volatility.
Let us be precise. The JCPOA, negotiated under Obama, was a triumph of multilateralism over unilateralism. It froze Iran's nuclear programme in exchange for sanctions relief. For British pension funds and FTSE 100 constituents with exposure to Gulf states, it was a known quantity. Predictable. Markets loathe uncertainty, and the JCPOA provided a framework. Oil prices stabilised around $50 a barrel, and the Tehran stock exchange saw a modest inflow of foreign capital. Not a free market paradise, but a workable equilibrium.
Enter Trump. His 'maximum pressure' campaign, including the re-imposition of secondary sanctions on any entity trading with Iran, is designed to choke off the Iranian economy. The logic is simple: deprive the regime of revenue to curb its regional meddling. But the market logic is reckless. Oil prices have already jumped 3% on the news. The risk premium on Gulf sovereign bonds has widened. And for British firms like BP or Rolls-Royce, which had cautiously re-entered Iranian markets, this is a slap of red tape. The cost of compliance just tripled.
More troubling is the signal this sends to capital markets. Investors crave consistency. The back-and-forth between two administrations highlights the fragility of American commitments. If the world's largest economy can unpick a major treaty on a whim, what faith can we place in any long-term contract? British gilts have long been a safe haven, but this turmoil adds a liquidity premium. The Bank of England will be watching the inflation expectations embedded in the yield curve. If the energy price shock feeds through, Threadneedle Street may have to tighten sooner than planned. That would hit mortgage holders and small businesses hardest.
Obama loyalists argue that the JCPOA was working, albeit imperfectly. Inspectors had access, uranium stockpiles were reduced. But Trump's team counters that the deal did nothing to constrain Iran's ballistic missile programme or its proxy wars in Yemen and Syria. Both arguments have merit, but from a balance-sheet perspective, the cost of tearing up the deal must be weighed against the benefits. The US Treasury estimates that sanctions will cost Iran $10 billion per year. But those same sanctions will also raise global oil prices, hurting American consumers and European manufacturers. For Britain, a net importer of energy, the hit is immediate.
My own view, forged over 20 years in the City, is that this is a classic case of political risk overwhelming economic rationality. The Trump administration has chosen a zero-sum game, betting that Iran will capitulate. History suggests Tehran will instead double down on its nuclear ambitions, perhaps expelling inspectors. That would trigger a crisis far worse than the current standoff. Investors should prepare for a prolonged period of volatility. Hedge oil exposure, reduce exposure to emerging-market debt, and watch the US dollar index. The only certainty is uncertainty.
As for the British government, it faces an unenviable choice. London has always been a champion of the JCPOA, but our special relationship with Washington means we cannot ignore the American stance. The Foreign Office will attempt a balancing act, but expect friction. British banks remain wary of Iranian transactions, and the secondary sanctions will only deepen that caution. For now, the market has spoken: the safe money is on a protracted stalemate, with capital fleeing towards the dollar and gold. Not a bet I would take lightly.
