() President Trump has warned Iran he will bomb their country should they not agree to a nuclear weapons deal to restrain the country’s nuclear program, after the Middle Eastern country said Sunday it rejected direct negotiations with the U.S.,

“If they don’t make a deal, there will be bombing and it will be bombing the likes of which they have never seen before,” Trump said in a comment aired Sunday on NBC News.

Trump also warned an imposition of “secondary tariffs” on Iranian oil would be possible, meaning countries who buy Iranian oil would be faced with U.S. tariffs.

“There’s a chance if they don’t make a deal, that I will do secondary tariffs on them like I did four years ago,” Trump said.

The president is attempting to curtail Iran’s rapidly advancing nuclear program, issuing a letter that arrived in Iran on March 12.

“I’ve written them a letter saying, ‘I hope you’re going to negotiate because if we have to go in militarily, it’s going to be a terrible thing,’” Trump told Fox Business earlier this month.