Araqchi said negotiations in Islamabad had been conducted in good faith but were undermined by what he described as “maximalism” and shifting U.S. demands, adding that the talks came close to producing an agreement before breaking down.

The remarks followed an announcement by Donald Trump that U.S. naval forces would begin blockading vessels entering or leaving Iranian ports, a move that risks destabilizing a fragile ceasefire reached after weeks of conflict.

US Central Command said the blockade would take effect at 10 a.m. ET (1400 GMT) and would apply to all maritime traffic linked to Iranian ports across the Arabian Gulf and Gulf of Oman, while maintaining freedom of navigation through the Strait of Hormuz for vessels not bound for Iran.

Trump said the United States would act against ships paying what he described as “illegal tolls” to Iran and warned that any attack on U.S. or commercial vessels would trigger a strong military response.

Iran’s Islamic Revolutionary Guard Corps said any approach by foreign military vessels to the strait would be treated as a violation of the ceasefire and met with a “decisive” response.

Parliamentary Speaker Mohammad Baqer Qalibaf dismissed the U.S. position, saying Tehran would respond in kind. “If you fight, we will fight, and if you come forward with logic, we will deal with logic,” he said, according to state media.

The talks in Islamabad marked the first direct engagement between the United States and Iran in more than a decade and followed a ceasefire announced earlier in the week after six weeks of conflict that has disrupted global energy markets and pushed oil prices above $100 per barrel.

JD Vance, who led the U.S. delegation, said no agreement had been reached, while signaling that diplomacy could continue. Trump also described the talks as “very friendly” and expressed confidence that Iran might return to negotiations.

A U.S. official said key sticking points included demands for Iran to halt uranium enrichment, dismantle enrichment facilities, transfer highly enriched material and end support for regional groups, alongside ensuring open access to the strait.

Iranian officials, including President Masoud Pezeshkian, said Tehran remained open to a “balanced and fair agreement,” blaming Washington for the breakdown and urging a return to international legal frameworks.

Shipping data showed that three fully laden supertankers transited the strait on Saturday, suggesting that maritime flows had not yet been fully disrupted despite the looming blockade.

The U.S. delegation, led by Vice President JD Vance and including special envoy Steve Witkoff and adviser Jared Kushner, was en route to the Pakistani capital after a stop in Paris. The Iranian side, headed by parliamentary speaker Mohammad Baqer Qalibaf and Foreign Minister Abbas Araghchi, arrived on Friday.

Qalibaf said Iran did not trust the United States based on past negotiations and warned that talks would not proceed unless Washington fulfilled earlier commitments, including unblocking Iranian assets and securing a ceasefire in Lebanon.

Iranian officials have linked progress in the talks to developments in the parallel conflict involving Hezbollah, a stance rejected by Washington and its allies.U.S. President Donald Trump said on social media that Iran “has no cards,” adding that Tehran’s leverage was limited to disrupting international waterways.

Vice President Vance, speaking en route, expressed cautious optimism about the negotiations but warned that the U.S. would respond firmly if it perceived bad-faith tactics.The talks come amid a fragile ceasefire announced earlier this week following weeks of U.S. and Israeli strikes on Iran and retaliatory actions by Tehran.

While the ceasefire has paused direct attacks, it has not resolved Iran’s blockade of the Strait of Hormuz, which continues to disrupt global energy flows.Pakistan imposed extensive security measures in Islamabad ahead of the negotiations, with Prime Minister Shehbaz Sharif describing the meeting as “make-or-break.” Thousands of security personnel were deployed across the city.

Parallel tensions persist in Lebanon, where Israeli operations against Hezbollah have continued despite diplomatic efforts. Lebanese President Joseph Aoun has called for a ceasefire as a condition for broader negotiations, while Israeli officials have signaled that upcoming talks with Lebanese representatives in Washington would proceed without linking them to a truce.

Iran has also pushed for broader concessions, including the lifting of sanctions and recognition of its authority over transit through the Strait of Hormuz, a proposal that would significantly alter regional power dynamics. While Iranian vessels were reported to be moving freely through the strait, shipping by other nations remains constrained.

The disruption to energy supplies has contributed to inflationary pressures and slowed global economic activity, with analysts warning that the impact could persist even if negotiations lead to a reopening of the route.Iran’s leadership has maintained a firm stance ahead of the talks.

Mojtaba Khamenei said Tehran would seek compensation for wartime damage and hold those responsible accountable.Despite U.S. claims of degrading Iran’s military capabilities, Tehran retains missile and drone capacity and a significant stockpile of highly enriched uranium, underscoring the challenges facing negotiators in reaching a comprehensive agreement.

Ishaq Dar said after meetings with regional counterparts that Islamabad was ready to facilitate “meaningful talks” toward a “comprehensive and lasting settlement,” including potential U.S.-Iran negotiations. It was not immediately clear whether either side had agreed to participate.

Iran’s parliament speaker Mohammad Baqer Qalibaf accused Washington of signalling openness to diplomacy while preparing for military escalation, saying Tehran would not accept demands amounting to surrender.U.S. officials have not publicly confirmed any agreement to attend talks.

Reports cited by U.S. media indicate the Pentagon is assessing options that could include ground operations, though no final decision has been announced by Donald Trump.

Discussions among regional powers, including Saudi Arabia, Turkey and Egypt, have focused on reopening the Strait of Hormuz, where Iranian restrictions on shipping since late February have disrupted global oil flows.

The conflict has driven oil prices sharply higher and intensified risks to maritime trade, with additional threats emerging near the Bab el-Mandeb Strait following attacks by Iran-aligned Houthi forces.

Israel said it carried out more than 140 air strikes across Iran over a 24-hour period, targeting missile infrastructure and other sites. Iranian media reported damage to Mehrabad airport in Tehran and a petrochemical facility in Tabriz.

Missile and drone exchanges have extended beyond Iran, with strikes reported in southern Israel near Beersheba and damage to industrial facilities in Gulf states including the United Arab Emirates and Bahrain.

The International Atomic Energy Agency said Iran’s heavy water production plant at Khondab had suffered severe damage and was no longer operational, though it contained no declared nuclear material.

The U.S. military has begun deploying thousands of Marines to the region, with the first contingent arriving aboard an amphibious assault ship, according to official statements.

Washington last week proposed a ceasefire framework that included reopening Hormuz and limiting Iran’s nuclear programme, but Tehran rejected the plan.

The conflict has triggered domestic political divisions in the United States, with protests reported in multiple cities and lawmakers offering sharply differing views on the war’s trajectory.