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.

Then came the June 2025 strikes by Israel and the U.S. on Iran’s nuclear facilities.

Successive rounds of indirect talks between the U.S. and Iran followed in early 2026. But despite an Omani mediator telling the world that a breakthrough was within reach, the U.S. bombed Iran on Feb. 28, 2026.

Mohammad Bagher Ghalibaf, Iran’s parliamentary speaker who led Iran’s delegation........

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