The average price of a gallon of regular petrol in the United States slipped below the psychologically significant $4 mark on Thursday for the first time since late March, settling at $3.999 according to motor club AAA. The overnight decline came hours after President Donald Trump signed a preliminary agreement with Iran, a diplomatic breakthrough that immediately rippled through global crude markets. For American motorists who had endured a peak of $4.56 in May, the threshold crossing offered tangible relief, though prices remain more than a dollar above pre-conflict levels.

The accord’s core provisions address both nuclear proliferation and energy security. Tehran committed to diluting its stockpile of highly enriched uranium, while Washington waived certain sanctions tied to Iranian oil exports. Crucially, the memorandum of understanding sets the stage for reopening the Strait of Hormuz, the narrow waterway through which roughly one-fifth of the world’s oil supply normally transits. The strait had been effectively closed since the eruption of hostilities on 28 February, when Trump ordered strikes on Iran, triggering a historic energy shock that sent crude prices soaring past $100 per barrel. On Thursday, benchmark crude fell more than 3 percent, dipping below $75 for the first time since the war’s opening trading day.

Viewed from Washington, the deal offers a reprieve from mounting domestic political pressure over fuel costs, with 28 states now averaging below $4 and Indiana recording the cheapest at $3.40. In Tehran, the promise of sanctions relief and renewed export revenue provides a powerful incentive for compliance, though hardliners remain sceptical of any pact with the White House. Analysts in London caution that the memorandum is only an initial framework; the full restoration of tanker traffic through Hormuz and the return of Iranian barrels to global markets will depend on sustained de-escalation. Meanwhile, the benefits are far from universal. In India, petrol prices have climbed 7 percent over the past three months, underscoring how regional subsidy structures and currency pressures can insulate or expose consumers to global swings.

Looking ahead, energy consultancy Rapidan Energy Group forecasts that US pump prices are unlikely to revisit the pre-war $3 threshold until 2027, citing persistently low inventory levels that will keep markets tight even as geopolitical tensions ease. A more meaningful decline is expected during the winter demand lull. For now, the tentative deal has injected a rare note of optimism into a jittery market, but the trajectory of prices remains hostage to the Strait of Hormuz’s full reopening and the durability of a peace that is still only sketched on paper.