The United States and Iran concluded high-level talks in Islamabad on Sunday without reaching an agreement, casting doubt on the continuation of a fragile two-week ceasefire amid a six-week conflict that has resulted in thousands of casualties and disrupted global oil markets.

The 21-hour negotiation marked the first direct, senior-level dialogue between Washington and Tehran since the 1979 Islamic Revolution. The meeting in Pakistan aimed to de-escalate the ongoing crisis, but both sides cited significant differences that prevented a breakthrough.

Iranian officials blamed “excessive” U.S. demands for the impasse, with Iranian media highlighting disagreements over control of the Strait of Hormuz and Tehran’s nuclear program as key stumbling blocks. Esmaeil Baghaei, spokesman for Iran’s Foreign Ministry, described the talks as conducted in a climate of profound mistrust and said it was unrealistic to expect a comprehensive agreement in a single round. He added that diplomacy would continue despite the current lack of progress.

On the U.S. side, Vice President JD Vance, who led the delegation, stated that Iran had rejected what he described as Washington’s final and best offer. Vance suggested the failure to reach a deal was more detrimental to Iran, but provided no specifics about the path forward after the 14-day truce expires.

The talks were mediated by Pakistan, with its Foreign Minister Ishaq Dar urging both parties to maintain the ceasefire and to seek lasting peace for the region. A Pakistani source described the discussions as tense and fluctuating in tone, reflecting the deep divisions between the delegations.

Iran’s delegation included Parliamentary Speaker Mohammad Bagher Ghalibaf and Foreign Minister Abbas Araghchi, signaling Tehran’s intent to engage seriously. Reports emerged that the U.S. might release some frozen Iranian assets held abroad, though a U.S. official denied confirming such a commitment.

Among Iran’s demands reportedly were full control over the strategic Strait of Hormuz, war reparations, and inclusion of a ceasefire in Lebanon—a demand rejected by Israel, which maintains that the Lebanon conflict lies outside the ceasefire terms. Israeli airstrikes on southern Lebanon continued over the weekend, contributing to the overall death toll topping 2,000 since fighting began.

Meanwhile, the Strait of Hormuz remains a critical and contentious focus in the conflict. The U.S. Navy announced the transit of two destroyers through the waterway ahead of planned mine-clearing operations, a move Iran’s military command denied. Iran’s Islamic Revolutionary Guard Corps warned it would respond decisively to any military vessels attempting passage.

Following the talks, President Donald Trump declared a U.S. naval blockade of the Strait of Hormuz, pledging to interdict any ships that pay tolls to Iran in international waters, further escalating tensions in the region.