The United States began enforcing a naval blockade of Iranian ports on Monday after high-level ceasefire negotiations in Pakistan ended without agreement, dramatically escalating tensions in the Strait of Hormuz — the narrow waterway connecting the Persian Gulf to the Arabian Sea that, before the conflict began, carried roughly 20 percent of the world's oil supply.
US Central Command announced that the blockade, effective from 10am Eastern Time on Monday, would apply to all vessels entering or leaving Iranian ports, while still permitting ships travelling between non-Iranian destinations to transit the strait. President Donald Trump framed the move in uncompromising terms. "It's going to be all or none, and that's the way it is," he told Fox News, adding that the Navy had been ordered to intercept any vessel that had paid tolls to Iran. Iran's Revolutionary Guard responded by asserting that the strait remained under Iran's "full control" and warning that military vessels would face a "forceful response." Iranian Parliament Speaker Mohammad Bagher Qalibaf, who led Tehran's negotiating team at the 21-hour talks, said simply: "If you fight, we will fight."
The Pakistan-hosted negotiations — the highest-level direct contact between Washington and Tehran since Iran's 1979 Islamic Revolution — broke down over several sticking points. The US side, led by Vice President JD Vance, demanded that Iran commit to never obtaining a nuclear weapon, halt uranium enrichment, dismantle major enrichment facilities, surrender its stockpile of highly enriched uranium, reopen the Strait of Hormuz, and end financial support for Hamas, Hezbollah, and Houthi rebels. Iranian officials acknowledged progress but said American "overreach" made full agreement impossible. Both sides indicated willingness to continue dialogue; Pakistan's Foreign Minister Ishaq Dar said Islamabad would seek to facilitate new talks within days. The ceasefire, in place since last Wednesday, is set to expire on April 22.
The crisis is rippling across the wider region. Bahrain on Monday summoned Iraq's chargé d'affaires to protest ongoing drone attacks originating from Iranian-aligned armed groups based in Iraqi territory — following a similar move by Saudi Arabia the day before. The attacks, which have targeted multiple Gulf Cooperation Council states and Jordan, have persisted despite those groups announcing a suspension of operations under the ceasefire terms. Baghdad has rejected the use of its territory for such strikes and offered to act on any evidence provided. Separately, UK Prime Minister Keir Starmer announced talks to be co-hosted with France this week, aimed at finding a diplomatic resolution and ensuring safe shipping through the Gulf.
Analysts are sceptical that a naval blockade will deliver Washington its objectives. Andreas Krieg, a senior lecturer in security studies at King's College London, said Trump lacked the military tools to force Iran's hand, arguing that concessions would likely be necessary. Meanwhile, the broader human cost of the conflict — which began on February 28 — now includes at least 3,000 dead in Iran, more than 2,000 in Lebanon, and dozens of fatalities across Gulf Arab states and Israel. The European Union has called for renewed diplomacy, Oman has urged "painful concessions" from all parties, and Russia has signalled readiness to help broker a settlement, underscoring how far the crisis has spread beyond its two principal protagonists.