Oil prices retreated after Iran's foreign minister said there had been "major progress" toward ending the fighting in Lebanon during the first session of high-level talks.
The president's warning underscores persistent tensions even as Vance said in Switzerland that he hoped the two sides would "turn over a new leaf" in their relationship.
U.S. Vice President JD Vance and top Iranian officials are trying to build out the interim deal to end the war in Iran reached by the two sides last week. They are meeting at a Swiss mountainside resort near Lake Lucerne.
The first peace talks between the United States and Iran were postponed Friday, as Vice President JD Vance cancelled his planned travel to Switzerland and intense new Israeli strikes in Lebanon cast doubts on the deal to end the war.
