Former U.S. President Donald Trump has announced that he started secret talks with Iran about a nuclear deal. During an interview on Fox Business on March 7, Trump said he sent a letter to Iran’s Supreme Leader, Ayatollah Ali Khamenei, hoping to begin negotiations.

Trump explained that he encouraged Iran to talk, saying, “I hope you’re going to negotiate because it will be much better for Iran.” However, he also warned that if Iran does not cooperate, the U.S. may have to take action.

So far, Khamenei has not publicly responded to Trump’s letter. In the past, Khamenei has dismissed the idea of reopening talks with the U.S. Last month, he stated that negotiations would not be “smart” and reminded Iranians that Trump had canceled the original nuclear deal in 2018.

Trump also issued strong warnings to Iran. He signed an executive order increasing pressure on the country and stated that if Iran assassinated him—following threats over the killing of Quds Force leader Qasem Soleimani—the U.S. would retaliate severely. “If they did that, they would be obliterated,” Trump said.

Trump suggested that there are only two ways to handle Iran—either making a deal or taking military action. He said he prefers making a deal because he does not want to harm Iran, adding that Iranians are “great people.”

However, Khamenei has urged Iranians not to trust the U.S., calling negotiations neither “smart, wise, nor honorable.” He also rejected Trump’s idea of the U.S. taking control of Gaza, saying such plans do not reflect reality.

It remains to be seen whether Iran will respond to Trump’s proposal or if tensions will continue to escalate.