Oil prices retreated on Monday, reversing earlier gains, 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 with the United States.

Pakistan and Qatar, which are mediating the negotiations in Switzerland aimed at securing a lasting peace agreement, said in a joint statement that “encouraging progress” had been made after the session concluded.

Oil prices had edged higher earlier in the day amid uncertainty over the status of the Strait of Hormuz, the narrow waterway between Iran and Oman that is a vital trading route for oil and natural gas that normally carries as much as one-fifth of the world’s oil supply. But optimism from the opening round of talks helped send oil prices lower.