DUBAI, United Arab Emirates — Iran and the United States began a fourth round of negotiations Sunday over Tehran’s rapidly advancing nuclear program , officials said, just ahead of a visit by President Donald Trump to the Middle East this week.

The latest round of high stakes nuclear talks between Iran and the US have ended, with Tehran calling them difficult but with both sides agreeing to further negotiations.

Oman's foreign minister says the fifth round of indirect talks between Iran and the United States will be held Friday in Rome. Neither Tehran nor Washington ha

Qatar on Tuesday said it was discussing ideas with Oman to try to bridge the remaining gaps in talks between Washington and Tehran as Iran's supreme leader cast doubts on whether negotiations would reach a conclusion.

Iran’s Supreme Leader Ayatollah Ali Khamenei said he does not expect negotiations with the United States over Tehran’s nuclear program to “reach a conclusion” as Washington toughens its conditions for a deal.

Diplomats from Iran and three European countries discussed their now-moribund 2015 nuclear deal in Istanbul on Friday, Iran's deputy foreign minister said, without giving details of any progress made.