The Islamabad talks were doomed to failure – and Hormuz blockade has thrown another obstacle to any Iran-US deal

Twenty-one hours of direct negotiations . The highest-level face-to-face engagement between Washington and Tehran since the 1979 Islamic Revolution.

And yet, U.S. Vice President JD Vance boarded Air Force Two in Islamabad on the morning of April 12, 2026, with no deal to end the U.S. and Israeli war against Iran, including an understanding over Tehran's nuclear ambitions.

The U.S. has since begun what it says is a blockade of any and all ships originating in Iranian ports and would interdict every vessel that has paid a toll to Iran.

The collapse of the talks wasn't the fault of bad faith or clumsy diplomacy. Rather, the talks failed because of structural obstacles that no amount of negotiating skill can overcome in a single weekend.

I and other exponents of international relations theory predicted this outcome . Understanding why matters enormously for what comes next.

The commitment barrier

The meeting in Islamabad wasn't the first time representatives from the United States and Iran have sat around a table. In 2015, the Joint Comprehensive Plan of Action agreed to by Iran, the U.S. and five other nations showed that a formal agreement with nuclear inspections and verification is possible.

But that deal, which saw sanctions on Iran relaxed in return for limits over Tehran's nuclear program, collapsed because the first Trump administration unilaterally walked away from the deal in 2018. In fact, the International Atomic Energy Agency had consistently certified Tehran was holding up its end of the bargain.

Iran has declared the blockade an act of "piracy" and placed the country on "maximum combat alert ," with the country's Revolutionary Guard warning that any military vessels approaching Hormuz would receive a "firm response ."

But like the nuclear negotiations, the blockade runs into the same wall. Iran controls the strait through mines, drones and geography. The U.S. can interdict ships but cannot reopen the strait without Iran's cooperation – absent an unlikely military occupation.

As such, the blockade is largely a pressure tactic without a clear path for how it would resolve, which is exactly the problem that produced the Islamabad failure in the first place. The blockade also holds the risk of pulling in more countries. Trump's interdiction order – "it's going to be all or none " – in theory means the U.S. Navy would be prepared to interdict a Chinese tanker that has done business with Iran, risking a direct maritime confrontation with a nuclear power.

The alternative would be to let Chinese tankers through to avoid confrontation, but in so doing expose the blockade as a hollow strategy.

In either case, Beijing has become an active stakeholder in Iran's leverage.

Same old problems … and a new one to boot

The structural obstacles that broke the Islamabad meetings will not dissolve before April 22, when the current ceasefire is due to expire.

The difficulty of convincing either side that any agreement will actually be honored will not be resolved by more talks, but is rather a product of what happened before the current negotiations. The nature of the nuclear question itself will not be negotiated away – it is a feature of physics and knowledge, not of political will. Moreover, Israel's veto over any regional settlement will not disappear because Washington wants a deal.

Signs suggest that talks are still alive, and both Iran and the U.S. have shown a willingness to change previous red lines on the nuclear question even since the failure in Islamabad. Absent a larger shift in the status quo, however, the next round will face the same structural obstacles as before. But this time, there will be the added complication of a naval blockade that narrows, rather than expands, the diplomatic space.

This article is republished from The Conversation , a nonprofit, independent news organization bringing you facts and trustworthy analysis to help you make sense of our complex world. It was written by: Farah N. Jan , University of Pennsylvania

Read more:

• 4 ways the war in Iran has weakened the United States in the great power game
• US ceasefire with Iran: What's next? A former diplomat explains 3 possible scenarios
• Failed peace deal: The Iran war has inflicted a cascade of losses that may never be recovered

Farah N. Jan does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

The Conversation

This story was originally published April 14, 2026 at 11:04 AM.