WASHINGTON/TEHRAN:

United States President Donald Trump on Sunday announced a naval blockade of the Strait of Hormuz following the end of Islamabad talks, a move that immediately triggered a sharp warning from Iran’s Islamic Revolutionary Guard (IRGC), which vowed a “forceful response” to any hostile action.

The escalation came after 21 hours of negotiations between the US and Iranian delegations, led by Vice President JD Vance and Parliament Speaker Baghar Ghalibaf, respectively, in Islamabad ended without an agreement or breakthrough.

In a post on his social media platform Truth Social, Trump thanked Pakistan for facilitating the dialogue, praising Prime Minister Shehbaz Sharif and military leadership for “extraordinary” hosting of the talks.

Trump said that he had been briefed by Vice President Vance, Special Envoy Steve Witkoff and adviser Jared Kushner, who were part of the US delegation at Saturday’s high stakes talks in the Pakistan capital.

“The meeting went well, most points were agreed to, but the only point that really mattered, nuclear, was not,” Trump wrote, adding that Iran remained unwilling to abandon its nuclear ambitions despite the productive engagement on other issues.

Trump said the talks, which began early and stretched through the night, demonstrated that while some areas of agreement had emerged, they were ultimately overshadowed by Tehran’s refusal to make concessions on nuclear enrichment, which the US views as the central obstacle to peace.Following the breakdown, Trump announced that the United States Navy would begin enforcing a blockade of the Strait of Hormuz, a strategic shipping route responsible for a significant share of global energy flows, saying the move would take effect “immediately.”

“The US Navy will begin the process of blockading any and all ships trying to enter or leave the Strait of Hormuz,” he said, adding that vessels paying “tolls” to Iran would be intercepted and that mines allegedly laid in the waterway would be cleared.

Trum warned that any Iranian forces targeting US or civilian vessels would face overwhelming military retaliation, while accusing Tehran of using the strait for “extortion” and destabilising global trade routes.

Speaking in a later Fox News interview, Trump said allied countries could support the blockade effort and claimed that minesweepers, including those from the UK and other nations, were being deployed to secure the waterway.

However, British media reports indicated that the UK won’t join Trump’s naval blockade on the Strait of Hormuz. “It is safe to say that none of the NATO member states will send a warship,” according to a Sky News report.

Iran rejected Washington’s position and doubled down on its control over the strategic passage. The IRGC warned that any military vessel attempting to transit the strait would face severe consequences, describing the area as being under Iranian operational authority.

Just hours later, US Central Command announced that it will begin implementing the blockade from Monday, saying that “the blockade will be enforced impartially against vessels of all nations entering or departing” the Iranian ports and coastal areas.

“US Central Command (CENTCOM) forces will begin implementing a blockade of all maritime traffic entering and exiting Iranian ports on April 13 at 10 a.m. ET, in accordance with the President’s proclamation,” it said on X.

It said that the blockade will include all Iranian ports on the Arabian Gulf and the Gulf of Oman, adding: “CENTCOM forces will not impede freedom of navigation for vessels transiting the Strait of Hormuz to and from non-Iranian ports.”

The command said it will notify commercial ships ahead of the blockade, advising all vessels in the Gulf of Oman and Strait of Hormuz to monitor maritime broadcasts and contact US naval forces if needed.

In a separate statement, the IRGC Navy said it maintained “full control” over the Strait of Hormuz and warned that any miscalculation would trap hostile forces in “deadly whirlpools,” while also releasing drone footage it said demonstrated surveillance dominance over the route.

Ali Akbar Velayati, a senior adviser to Iran’s Supreme Leader, said the strait was “firmly in our hands” and stressed that Tehran’s diplomatic approach remained focused on protecting national sovereignty and strategic interests following the failed talks in Pakistan.

Iranian President Masoud Pezeshkian, according to state media reports, said Tehran sought a “balanced and fair agreement” and remained open to dialogue, but insisted that any settlement must respect Iran’s rights and legal position on its nuclear programme.

“If the US government abandons its authoritarian approach and respects the rights of the Iranian people, ways to reach an agreement will certainly be found,” he posted on X handle. “I commend the members of the negotiating team, especially my dear brother Dr Qalibaf, for their efforts.”

Pezeshkian, in a phone call with Russian President Vladimir Putin, told him that the “biggest obstacle” to achieving a fair agreement with the US was “America’s all-or-nothing demands”, adding: “Our red line is Iran’s national interests and the rights of the Iranian nation,” he said.

Parliament Speaker Bagher Ghalibaf, who led Iran’s side at the peace talks in Pakistan, said that his country will not give in to Trump’s threats. “If they fight, we will fight, and if they come forward with logic, we will deal with logic,” he told reporters in Tehran.

“We will not bow to any threats, let them test our will once again so that we can teach them a bigger lesson,” Ghalibaf said after returning from Islamabad, according to several Iranian news agencies.

Iranian officials also argued that the failure of the Islamabad talks stemmed from unresolved differences on two to three key issues, including sanctions relief, nuclear enrichment and control over the Strait of Hormuz, while maintaining that no agreement was expected in a single round.

Despite the collapse of negotiations, both sides left the door open to further diplomatic engagement, even as tensions rose sharply over the naval blockade announcement and the risk of escalation in a region already strained by months of conflict.

The talks in Islamabad ended without a deal or clear roadmap for the next round of diplomacy, leaving a fragile ceasefire under renewed pressure as international actors warned that further escalation could destabilise global energy markets and widen the conflict.