President Donald Trump said on Wednesday that Iran’s Supreme Leader Ali Khamenei “should be very worried” as negotiations planned for this week grow increasingly uncertain.

“He should be very worried. Yeah, he should be. As you know, they’re negotiating with us,” Mr Trump said in excerpts from an interview with NBC News slated to air later.

The comments came as Mr Trump ordered an ongoing mass military buildup in the Middle East region as he seeks to pressure Iran to meet him at the negotiating table.

Asked about Iranian protesters, the U.S. president said, “We’ve had their back.”

Mr Trump added, “That country is a mess right now because of us. We went in, we wiped out their nuclear. Peace in the Middle East. If I didn’t take out their nuclear, think of it.

“If we didn’t take out that nuclear, we wouldn’t have peace in the Middle East, because the Arab countries could have never done that. They were very, very afraid of Iran.”

Mr Trump was referring to strikes he ordered on Iran’s nuclear facilities during the 12-day Iran-Israeli war in June.

News website Axios reported earlier Wednesday that the U.S. told Iran it would not agree to Tehran’s demands to change the location and format of talks scheduled for Friday.

The report came after Iranian media said the indirect talks between Iran and the U.S. were set to take place on Friday in Oman’s capital Muscat. Discussions were expected to focus on Tehran’s nuclear programme and the lifting of sanctions.

Istanbul, Türkiye, was the planned venue for the nuclear talks between the U.S. and Iran.

According to Axios, the official said that if the Iranians were willing to return to the original format, the U.S. was ready to meet this week or next.

Earlier, U.S. secretary of state Marco Rubio said that the venue for talks with Iran was “still being worked through”.

He added that discussions must address Tehran’s ballistic missiles, nuclear programme, regional “sponsorship of terrorist organisations” and the treatment of its people.

“We thought we had an established forum that had been agreed to in Türkiye,” he said. “It was put together by a number of partners, who wanted to attend and be a part of it. I saw conflicting reports yesterday from the Iranian side saying that they had not agreed to that, so that’s still being worked through.”

Oman has previously served as a mediator in indirect contacts between the two sides.

In recent days, several countries have stepped in and offered to mediate between Tehran and Washington to ease tensions, with Türkiye playing a particularly active role.

The U.S. and its ally, Israel, accuse Iran of seeking to produce nuclear weapons, while Tehran says its nuclear programme is designed for peaceful purposes, including electricity generation.

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