U.S.-Iran Nuclear Talks Stall as Hormuz Ceasefire Frays

Secretary of State Marco Rubio told reporters in Rome that the United States is awaiting an Iranian response to its latest proposal to end the ongoing conflict, even as a fresh military exchange in the Strait of Hormuz cast doubt on the durability of the existing ceasefire. Rubio said Washington expects a reply from Tehran within the day and described the goal as establishing "a serious process of negotiation" [POLITICO]. The statement came against the backdrop of the fifth round of indirect, Omani-mediated nuclear talks, which concluded on May 23 with Omani Foreign Minister Badr al-Busaidi describing the outcome as showing "some, but not conclusive, progress." ^[1][2]

The core dispute remains uranium enrichment. The Trump administration has demanded Iran halt all domestic enrichment activity, a position U.S. Middle East Envoy Steve Witkoff hardened in recent days by declaring that Washington "cannot allow even 1 percent of an enrichment capability." ^[3] Iranian Supreme Leader Ali Khamenei publicly rejected that demand, and Foreign Minister Abbas Araghchi drew an explicit line before flying to Rome, posting that "zero enrichment = we do NOT have a deal." ^[4][3] Iran has enriched uranium to 60 percent purity, a short technical step from weapons-grade, since abandoning the limits of the 2015 Joint Comprehensive Plan of Action after the United States withdrew from that agreement in 2018. ^[5] The Trump administration has conditioned any new deal on Iran surrendering its enriched stockpile, shuttering three nuclear facilities, and suspending enrichment for up to 20 years, according to three Iranian officials who spoke to The New York Times. ^[6] Iran has countered by proposing to dilute its uranium and transfer it to a third country, possibly Russia, and to suspend enrichment for a shorter period. ^[6]

Military activity at sea is now running in parallel with the diplomacy. U.S. Central Command confirmed that Iranian forces launched "multiple missiles, drones and small boats" against the USS Truxtun, USS Rafael Peralta, and USS Mason as the three guided-missile destroyers transited the Strait of Hormuz toward the Gulf of Oman. ^[7][8] CENTCOM said U.S. forces intercepted all inbound threats, that no U.S. assets were struck, and that American forces then responded with "self-defense strikes" on Iranian military facilities, including missile and drone launch sites, command and control locations, and intelligence, surveillance, and reconnaissance nodes. ^[7][9] Iran's military contested CENTCOM's account, asserting that its forces fired only after the United States violated the ceasefire by attacking an Iranian oil tanker. ^[10] The United Arab Emirates separately reported that its air defenses engaged a barrage of Iranian ballistic missiles and drones directed at UAE territory. ^[11] CENTCOM also disclosed that U.S. forces struck two Iranian-flagged oil tankers attempting to violate the American blockade of Iranian ports, which has been in effect since mid-April. ^[12][11]

The competing characterizations of Thursday's exchange go to the legal and operational status of the ceasefire itself. President Trump told ABC News the strikes were "just a love tap" and insisted the ceasefire remains in effect. ^[13] Defense Secretary Pete Hegseth similarly told reporters the ceasefire is still in place, and Rubio confirmed that Operation Epic Fury, the initial U.S. military campaign against Iran, has ended. ^[14] Iran's position, as stated by Araghchi on social media, is that each U.S. military action undermines the diplomatic track, framing the parallel use of force as either a deliberate pressure tactic or the work of unidentified internal "spoilers" [POLITICO]. The legal basis for U.S. naval interdiction of Iranian-flagged commercial vessels rests in part on the executive blockade authority invoked after the collapse of earlier Islamabad-based talks in April and the subsequent presidential declaration of a naval blockade of Iranian ports. ^[12]

The talks themselves follow a trajectory of incremental process and widening gaps. The first round of negotiations opened in Oman on April 12, led by Witkoff and Araghchi, following a letter from President Trump to Iranian Supreme Leader Ali Khamenei. ^[15] Subsequent rounds were held in Rome and Muscat, with Oman's foreign ministry serving as mediator throughout. ^[15][2] More than 200 Republican lawmakers wrote a letter on May 14 pressing the administration to maintain a strict zero-enrichment posture, a development that Iranian officials cited as one more signal of U.S. inflexibility. ^[3] Two Iranian sources told CNN that Tehran's participation in the fifth round was primarily to gauge Washington's position rather than to pursue a concrete agreement, and that the U.S. insistence on full dismantlement of the enrichment program is the obstacle most likely to collapse the negotiations. ^[16] Al-Busaidi said after Friday's talks that the parties "hope to clarify the remaining issues in the coming days," but no date or venue for a sixth round has been announced. ^[1][2]

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