American and Iranian officials were holding face-to-face talks in Pakistan on Saturday, the most significant since the 1979 Islamic revolution as the foes try to end a war that plunged the Middle East into violence and rocked the world economy.

U.S. President Donald Trump vowed Friday to have the Strait of Hormuz open "with or without" Iran's cooperation, and said his top priority in peace talks was to ensure Tehran can't have a nuclear weapon.

U.S. Vice President JD Vance arrived in Islamabad on Saturday for talks with Iran that the Pakistani premier hosting the warring sides called a "make or break" effort to permanently halt weeks of fighting in the Middle East.

Iran demanded a truce in Lebanon and the release of its blocked assets on Friday as U.S. Vice President JD Vance warned Tehran not to "play" Washington, casting doubt on planned ceasefire talks in Pakistan.

Iran's new supreme leader Mojtaba Khamenei said in his latest written message the Islamic republic did not want war with the United States and Israel, but would protect its rights as a nation, state television reported Thursday.

U.S. President Donald Trump on Thursday accused Iran of doing a "very poor job" of allowing oil through the Strait of Hormuz and of breaching the terms of their two-week ceasefire agreement.

In a barrage of social media posts that sparked fresh fears for the shaky truce, Trump also warned Iran against imposing a toll for ships passing through the crucial waterway.

Pakistan was poised on Friday to host Iranian and U.S. delegations for negotiations in its capital, although Tehran's participation remained uncertain after deadly Israeli strikes on Lebanon threatened this week's temporary truce.

U.S. President Donald Trump told NBC News on Thursday he was "very optimistic" about a peace deal with Iran after their ceasefire, and that Israel was "scaling back" strikes in Lebanon.

Iran's parliament speaker on Thursday said Lebanon was a key part of the two-week ceasefire with the United States, warning that violations would bring severe consequences, following massive Israeli strikes on Lebanon.

Israel vowed more strikes against Hezbollah on Thursday, dismissing mounting international demands that the fragile truce between the United States and Iran in the Gulf be expanded to cover the war in Lebanon.