The United States military has announced plans to commence a blockade of all Iranian ports on Monday, following the collapse of high-stakes negotiations between Washington and Tehran in Pakistan.

The development marks a sharp escalation in tensions, with US President Donald Trump blaming Iran’s refusal to abandon its nuclear ambitions for the breakdown in talks.

Trump disclosed on social media that the US would enforce a blockade of the strategic Strait of Hormuz, a critical global shipping route, after his Vice President, JD Vance, withdrew from negotiations with an Iranian delegation in Islamabad on Sunday.

The failure of the negotiations has dashed global hopes of ending the war, which has reportedly claimed thousands of lives and disrupted the global economy since it erupted in late February.

Although Pakistan, which mediated the talks, pledged to continue facilitating dialogue, it urged both sides to respect the fragile two-week ceasefire agreed upon last week.

Analysts, however, warned that the proposed maritime blockade could undermine the truce.

US Outlines Scope Of Blockade
In a statement, the US Central Command said the blockade would take effect at 1400 GMT on Monday.

“The blockade will be enforced impartially against vessels of all nations entering or departing Iranian ports and coastal areas, including all Iranian ports on the Arabian Gulf and Gulf of Oman,” AFP quoted the statement as saying.

It clarified that US forces would not obstruct vessels transiting the Strait of Hormuz to and from non-Iranian ports.

Trump, confirming the move on his Truth Social platform, struck a more aggressive tone.

“Effective immediately, the United States Navy, the finest in the world, will begin the process of BLOCKADING any and all ships trying to enter, or leave, the Strait of Hormuz,” he said.

“Any Iranian who fires at us, or at peaceful vessels, will be BLOWN TO HELL!”

Iran Fires Back, Rejects US Threats
Iran reacted swiftly, rejecting the US move and issuing strong warnings.

Speaker of Iran’s parliament, Mohammad Bagher Ghalibaf, said Tehran would “not bow to any threats,” while navy chief Shahram Irani described Trump’s blockade threat as “ridiculous.”

Iran’s Revolutionary Guards had earlier warned that they maintained full control over traffic through the Strait of Hormuz and could trap any aggressor “in a deadly vortex.”

Meanwhile, Iran’s Foreign Minister, Abbas Araghchi, accused the US of frustrating a near-agreement.

He cited “maximalism, shifting goalposts, and (a) blockade” as factors that derailed talks, which he claimed were “just inches away” from success.

Global oil markets reacted sharply to the escalation, with prices jumping by about eight per cent on Monday.

Both Brent crude and West Texas Intermediate (WTI) reportedly surged past $100 per barrel, reversing last week’s decline following the temporary ceasefire.

The Strait of Hormuz, a vital artery for global oil and gas shipments, remains at the centre of the crisis.

Although the US said it would not block access to non-Iranian ports, Tehran has already imposed restrictions, allowing only select vessels, including those linked to friendly nations such as China, to pass.

A report by Iran’s Fars news agency indicated that two Pakistan-flagged oil tankers had turned back from the strait on Sunday.

Security concerns escalated further after the US military claimed that two Navy warships had entered the strait to clear mines, a claim Iran denied.

Nicole Grajewski, a researcher at Sciences Po, described the blockade as a major escalation.

“A US blockade is not a minor coercive signal,” she said, warning it could effectively mark a resumption of full-scale war.

The US delegation in Islamabad, which included Vance, special envoy Steve Witkoff, and Trump’s son-in-law Jared Kushner, reportedly grew frustrated over Iran’s insistence on maintaining its nuclear programme.

“I have always said… IRAN WILL NEVER HAVE A NUCLEAR WEAPON!” Trump reiterated in a post.

Vance told reporters that Washington had presented Tehran with its “final and best offer.”

“We’ll see if the Iranians accept it,” he said.

Trump, however, appeared indifferent about the future of negotiations.

“I don’t care if they come back or not. If they don’t come back, I’m fine,” he stated.

Beyond the Gulf, tensions continue to escalate in Lebanon, threatening the fragile ceasefire.

Lebanese Prime Minister Nawaf Salam said efforts were ongoing to halt hostilities and secure the withdrawal of Israeli forces.

However, Israeli Prime Minister Benjamin Netanyahu insisted that military operations would continue.

Hezbollah confirmed it had launched rockets into northern Israel overnight, sustaining attacks it began in March.

The group said the attacks were in response to the killing of Iran’s supreme leader during the initial Israeli-US strikes that triggered the wider regional conflict.

Israeli airstrikes on Beirut and other parts of Lebanon last week reportedly killed hundreds, according to local health authorities.

With diplomacy stalled and military actions intensifying, fears are mounting over a broader regional conflict.