Twenty-one hours of marathon negotiations between American and Iranian delegations in Islamabad have ended without agreement, triggering an immediate and dangerous escalation: US President Donald Trump announced a naval blockade of the Strait of Hormuz, and Iran's Islamic Revolutionary Guards Corps (IRGC) — the elite military force that controls the waterway — warned that any military vessels attempting to enter the strait would be treated as a violation of the fragile two-week ceasefire between the two countries.

The talks, held on Saturday and into Sunday and mediated by Pakistan, were historically significant in their own right: they represented the first face-to-face meeting between senior American and Iranian officials in more than 47 years, a product of 39 days of open conflict that began when the United States and Israel launched strikes on Iran on February 28. US Vice President JD Vance led the American delegation, which included advisers Steve Witkoff and Jared Kushner and CENTCOM commander Admiral Brad Cooper. Iran was represented by Parliament Speaker Mohammad Bagher Ghalibaf, Foreign Minister Abbas Araghchi, and National Security Council Secretary Mohammad Bagher Zolghaddr, alongside central bank and military experts. Pakistan's Prime Minister Shehbaz Sharif and army chief Field Marshal Asim Munir played an active role that went beyond traditional mediation, positioning Islamabad as a genuine security guarantor rather than a neutral go-between. The two sides exchanged competing frameworks — a 15-point American proposal against a 10-point Iranian counter-plan — but could not bridge the gap on nuclear issues, with Vance saying no concessions were possible without long-term guarantees and Araghchi calling US demands excessive. Iran's foreign ministry spokesperson said understanding was reached on several points, but that views on two or three critical issues remained