US President Donald Trump has announced what he described as "the most crushing economic operation ever taken against any country," threatening sweeping economic consequences against any nation that continues to do business with Iran. The declaration, posted on his Truth Social platform, signals a deliberate shift in Washington's strategy away from military strikes and toward economic strangulation — though critics and analysts note the announcement was conspicuously short on specifics.

"Any country that allows its financial institutions, businesses, airports, or government entities to provide any type of lifeline to Iran will itself face tremendous economic consequences," Trump wrote, calling the move an "Economic D-Day." He listed activities that must stop immediately, including "oil smuggling, swap lines, cash transfers, exchange houses, ship registries, front companies" — language that strongly implies secondary sanctions targeting Iran's trading partners. No specific countries were named, and no concrete penalties were spelled out.

The announcement comes as the US-Iran war approaches its sixth month — the conflict began on 28 February with US-Israeli strikes on Iran, which responded with missile and drone attacks across the region. Months of nightly American strikes failed to bring Tehran back to the negotiating table, and Pentagon advisers reportedly told Trump last month that the US had nearly exhausted viable military targets and had significantly drawn down its munitions stockpiles, though the Pentagon has publicly denied those reports. The White House has since signalled a turn toward economic pressure. Treasury Secretary Scott Bessent confirmed last week that the US would intensify efforts to isolate Iran economically, working alongside a US naval blockade of the Strait of Hormuz — the narrow waterway between the Persian Gulf and the Gulf of Oman through which a substantial share of the world's oil passes. An ongoing US Treasury campaign called Operation Economic Fury has already been targeting Iran's funding through targeted sanctions.

The most immediate complication is China. Iran's biggest trading partner purchases significant volumes of Iranian oil, often through a sophisticated network of shadow tankers that has allowed Tehran to partially circumvent existing Western sanctions. Analysts warn that any serious attempt to enforce secondary sanctions could provoke a direct confrontation with Beijing — particularly sensitive given that Chinese President Xi Jinping is expected to visit the United States next month. "Whatever new economic measures the US can use will need to be directed at Iran's trading partners," said Gregory Brew, a senior analyst at the Eurasia Group, adding that it would be "hard for the US to direct such actions at China, the country that matters most to Iran's economic future."

Iran has responded with defiance. An adviser to Supreme Leader Ayatollah Ali Khamenei said military pressure and sanctions would not break Tehran's resolve, while the country's foreign minister reached out to Pakistani and Mauritanian counterparts to shore up diplomatic ties. Gulf allies of the US, meanwhile, are reportedly concerned that mounting economic pressure will provoke a fresh Iranian military response, reigniting the broader conflict. The United Arab Emirates, historically one of Iran's largest trading partners accounting for over 30 percent of its imports, announced on Tuesday that it was suspending all trade and financial transactions with Iran after reporting two ballistic missiles were launched from Iranian territory — a claim Tehran dismissed as baseless. Trump is also facing growing domestic pressure as November midterm elections approach, with US consumers and lawmakers scrutinising the war's economic and human costs.