ISLAMABAD — The United States and Iran met in Islamabad, Pakistan, over the weekend but failed to reach a deal, with the two sides unable to bridge a gap over how long Iran should suspend its uranium enrichment program. The U.S. insisted that Iran halt enrichment for 20 years in exchange for sanctions relief, while Iran refused to agree to a moratorium beyond five years.

Pakistan is attempting to get both sides to come to a second round of talks. The disagreement over the duration of an enrichment suspension was the central sticking point in ceasefire talks between the two governments.

The dispute over Iran's nuclear program has deep roots. Israel and the U.S. have accused Iran of enriching uranium to develop nuclear weapons, while Iranian officials have maintained that the enrichment program is solely for civilian energy purposes. Iran has enriched uranium to levels beyond those required for civilian energy, and Iranian officials have expressed willingness to discuss reducing enrichment levels but have refused to dismantle the program entirely.

MV Ramana, a professor in disarmament, global and human security at the University of British Columbia, said in an interview: "Both the US and Iranian governments have staked a lot of political capital on Iran's enrichment programme. The dispute in recent years and months has been that Trump wanted Iran to completely abandon the programme, and Iran refusing to ever do that." Ramana added: "Now they have moved a little from that position and are trying to stake out positions that are somewhat closer to each other. Beyond that, I cannot discern any technical reasons for either 20 or five years."

The U.S. and its European allies have imposed multiple rounds of sanctions on Iran over the enrichment issue. In 2015, Iran agreed to the Joint Comprehensive Plan of Action, negotiated under President Barack Obama, under which it committed to limiting uranium-235 enrichment to 3.67% for 15 years, keeping its enriched uranium stockpile below 300 kilograms, and not building new centrifuges for 10 years. Enrichment to 3.67% is sufficient to fuel civilian nuclear plants and is below the level needed for weapons. In 2018, President Donald Trump withdrew the U.S. from the JCPOA and reimposed sanctions. At the time of the withdrawal, Iran was fully compliant with its commitments, according to the IAEA and U.S. intelligence agencies.

Since 2018, Trump has repeatedly stated that Iran should not have the ability to produce nuclear weapons. The U.S. cited that demand as the central justification for bombing Iranian nuclear facilities during a 12-day war with Israel in June 2025 and as one of the reasons for initiating a war with Iran in February 2026. Underground nuclear facilities at Isfahan, Natanz, and Fordow were destroyed or badly damaged in those strikes, and the sites have been targeted again during the current conflict.

Iran is believed to have about 440 kilograms of uranium enriched to 60%, a level that reduces the additional enrichment needed to reach weapons-grade status. IAEA chief Rafael Grossi has said that quantity is theoretically enough to produce more than 10 nuclear warheads. Approximately half of that stockpile is believed to be stored in an underground tunnel complex at Isfahan, with an unknown quantity at Natanz, according to Grossi. It is unclear whether those stockpiles survived the strikes or what condition they are in. Trump has considered deploying U.S. special forces to Iran to seize the country's stockpile of highly enriched uranium.