A high-stakes diplomatic gamble has failed — and the global economy is now on edge.

The collapse of marathon US-Iran negotiations has triggered fresh fears of a prolonged energy crisis, with oil prices poised to spike and borrowing costs expected to climb as early as this week. With tankers stranded and tensions escalating in the Gulf, markets are bracing for a volatile and potentially costly fallout.

Energy Markets On Edge

The failure to secure a peace deal has left energy markets rattled. Oil and gas prices are already flashing warning signs of another surge, as supply disruptions ripple outward. At the center of the crisis: a breakdown in talks after 21 hours of intense negotiations in Islamabad.

US Vice President JD Vance placed the blame squarely on Tehran, accusing it of refusing to abandon its nuclear weapons programme. Iranian officials fired back, criticizing Washington’s “excessive” demands. The impasse now threatens to prolong a war that erupted on 28 February following US and Israeli airstrikes on Tehran.

Oil Prices Signal Trouble Ahead

As the diplomatic window slammed shut, early market signals pointed to rising oil prices. A weekend trading indicator from broker IG showed US crude climbing toward $98 a barrel — up from $96.50 before the talks — with further gains likely once markets fully reopen.

“Unless a sudden U-turn emerges, energy markets are set for a rocky open when regular trading resumes tomorrow morning,” said Tony Sycamore, market analyst at IG Australia.

Major financial institutions are already sounding alarms. Analysts at JPMorgan Chase expect oil prices to remain elevated above $100 a barrel through the second quarter before easing later in the year.

Last week’s price swings underscored the fragility of the situation. Oil briefly dipped below $100 following a temporary two-week ceasefire, but volatility dominated. Brent crude closed the week at $94.26 — far below its wartime peak of $119.45, yet still significantly higher than the roughly $72 level before the conflict began.

Escalation Risks Return

Now, the risk of escalation is back in focus.

On Sunday, US President Donald Trump warned that the absence of a deal would trigger a blockade of the strategically critical Strait of Hormuz — a chokepoint for global oil flows that Iran has effectively shut. Reopening the strait had been a key element of last week’s truce.

Iran signaled it remains firmly in control. Deputy parliament speaker Haji Babaei said the passage is “completely” under Iranian authority and insisted that any transit would require toll payments in rials.

In a fiery Truth Social post, Trump escalated rhetoric further, declaring the US would begin “BLOCKADING any and all Ships trying to enter, or leave, the Strait of Hormuz”.

He added that the US navy would start “destroying the mines the Iranians laid in the straits”, warning that any Iranian who fires at US forces or “peaceful vessels will be blown to hell”.

Global Economic Shockwaves

The economic consequences are already rippling globally.

Governments are increasingly concerned about a renewed inflation surge driven by rising energy costs. Central banks, which had been preparing to cut interest rates, are now reconsidering — with financial markets beginning to price in rate hikes instead.

The strain is being felt on the ground. In Ireland, protests erupted across Dublin over the rising cost of living, highlighting growing public frustration as energy prices climb.

Mohamed El-Erian, adviser to Allianz and former president of Queens’ College, Cambridge, warned that uncertainty will dominate the global financial outlook.

“While both parties stressed that a quick agreement was too much to hope for given the issues involved, neither readily indicated the next step – something the whole world will be focused on, especially as Israel’s attacks on Lebanon continued throughout the weekend,” he said.

He added: “Absent a swift resumption of negotiations, the immediate reaction of financial markets when they open for the trading week will be to push oil prices higher and borrowing costs higher.

“The extent of the sell-off in the stock market, where investors have been consistently more optimistic than in other asset classes, will depend on whether they see a viable path to further diplomacy.

“For the UK, all this translates into another hit to the cost of living and less flexibility for both fiscal and monetary policy responses.”

Fragile Hopes Collapse

The week had begun with stark warnings from Trump, who threatened that “a whole civilisation will die tonight, never to be brought back again” through strikes on Iran’s infrastructure. That scenario was narrowly avoided when a fragile two-week truce was brokered by Pakistan — but hopes of lasting peace have now faded.

Global stock markets initially rallied on news of the ceasefire. By week’s end, the S&P 500 had nearly recovered to pre-conflict levels and remained flat for the year — a sign of cautious investor optimism that may now be tested.

Supply Struggles And Limited Relief

Meanwhile, Saudi Arabia has scrambled to stabilize supply. Officials said the kingdom had restored key infrastructure, including its east-west pipeline, after Iranian attacks disrupted production. The Saudi Press Agency reported a temporary loss of around 700,000 barrels per day, with efforts ongoing to return to full capacity at the Khurais oilfield.

There were small signs of movement in the Gulf. On Saturday, three fully loaded supertankers passed through the Strait of Hormuz — likely bound for China — marking the first such transit since the ceasefire.

But analysts warn against optimism.

Wei Yao, economist at Société Générale, said: “Even if the ceasefire frays, the more likely near-term outcome, in our view, is messy non-compliance and low-level retaliation near-term, rather than an immediate return to full-blown escalation. For the global economy, this means lasting disruptions, as oil and LNG flows would normalise only slowly.”

Global Focus Shifts To Fallout

The broader economic fallout is now set to take center stage.

The International Monetary Fund and World Bank begin their spring meetings in Washington on Monday, with the war expected to dominate discussions. IMF Managing Director Kristalina Georgieva has indicated the fund will present three scenarios — all pointing to slower growth and higher inflation, with particularly severe consequences for vulnerable economies.

For now, one thing is clear: the collapse of diplomacy has reignited fears of an energy shock that could ripple through every corner of the global economy.