Tehran, April 13 : Iran has accused the United States of derailing a potential breakthrough agreement, saying that "maximalism, shifting goalposts, and blockade tactics" prevented what was "inches away" from becoming the proposed "Islamabad MoU", after 21 hours of intense negotiations ended without a deal.

In a post on X, Iranian Foreign Minister Abbas Araghchi said Tehran had entered into its highest-level direct engagement with Washington in 47 years with sincerity and intent to help bring an end to the ongoing conflict, but lamented that there were "zero lessons earned".

His assertion that both sides were "inches away" from finalising an agreement highlighted how close the talks had come to success before tensions escalated sharply at the final stage.

"In intensive talks at highest level in 47 years, Iran engaged with US in good faith to end war. But when just inches away from 'Islamabad MoU', we encountered maximalism, shifting goalposts, and blockade. Zero lessons earned. Good will begets good will. Enmity begets enmity," Araghchi posted on X.

Iranian President Masoud Pezeshkian said that the possibility of a diplomatic breakthrough with the United States still exists, provided Washington changes its approach. He urged the US to abandon what he termed "totalitarianism" and to respect Iran's rights, suggesting that such a shift could pave the way for an agreement.

"If the American government abandons its totalitarianism and respects the rights of the Iranian nation, ways to reach an agreement will certainly be found," Pezeshkian said in a post on X, while praising members of the negotiating delegation.

Meanwhile, the United States announced that it will begin enforcing a sweeping maritime blockade of vessels entering or exiting Iranian ports from April 13, escalating tensions after high-stakes talks between Washington and Tehran failed to yield agreement on key issues, including Iran's nuclear programme.

The move, announced by US Central Command (CENTCOM), follows a presidential directive and will target "all maritime traffic entering and exiting Iranian ports", including those along the Arabian Gulf and Gulf of Oman.

"The blockade will be enforced impartially against vessels of all nations," CENTCOM said, adding that US forces would not impede ships transiting the Strait of Hormuz to and from non-Iranian ports.

Commercial mariners have been advised to monitor official navigation warnings and remain in contact with US naval forces while operating in the region.

The announcement came hours after US President Donald Trump declared that negotiations with Iran had stalled over its nuclear ambitions, despite progress on other fronts.

/IANS