Negotiations to end the war are at an impasse over Iran’s nuclear program and the Strait of Hormuz, which remains mostly shut.
Each side is betting it can last longer than the other, analysts say. But there are risks in a stalemate without a deal.
The last-minute scuttling of the trip to Pakistan was the latest sign of how far apart the two sides are on reaching a deal to end the Iran war.
President Trump withdrew from the Obama-era nuclear accord in 2018, saying it was the worst deal ever. But Iran responded with an enrichment spree that haunts the negotiations to this day.
President Trump has outsourced much of his diplomacy to others, while Mr. Rubio focuses on his second job as national security adviser.
Iran’s foreign minister has already arrived in the country, state media reported. He was believed to be carrying a written response to a U.S. proposal to end the war.
As the United States and Iran make a second attempt at a deal, their negotiating styles are on a collision course.
At least 70 people are in the team that is scheduled to negotiate with the American side in Pakistan on Saturday.
President Trump’s cease-fire with Iran appears at risk as Vice President JD Vance heads to Pakistan for discussions with Iranian officials.
Vice President JD Vance is leading negotiations this weekend toward an end to a war that he had opposed starting.