Eyeing a second round of U.S. talks, Iranian officials said they were willing to discuss nuclear issues but drew a red line on ballistic missiles.

An adviser to Iran’s supreme leader says Iran is unwilling to compromise on its missile capabilities, pointing to a potential sticking point in talks with the United States.

Ali Shamkhani made the statement on Wednesday at an event marking the 47th anniversary of the Islamic Revolution. “The Islamic Republic’s missile capabilities are non-negotiable,” he was quoted as saying by state media.

His remarks follow a round of mediation talks Talks between U.S. and Iranian officials in Oman last week failed to produce a breakthrough. Iran wants the talks to be devoted to nuclear issues, while the United States pushes to address Iran’s ballistic missile program and regional alliances.

“The Iranians say we are ready to talk about nuclear, but we are not ready to talk about ballistics,” Al Jazeera’s Ali Hashim reported from Tehran, Iran. “This is a big problem for the United States.”

Many Iranians still have memories of last June 12 days of war with Israel About 610 people have been killed in the country, and there are fears a renewed conflict could erupt. “A lot of people here are very concerned that this could lead to adverse outcomes,” Hashim said.

“Will not succumb to aggression”

Washington and Tehran are considering another round of talks, but a date has not yet been announced.

U.S. President Donald Trump has sent mixed signals about the negotiations. While he said the first round was “really good,” he also threaten military action If Iran does not meet U.S. demands.

“Either we get a deal or we’re going to have to take some very tough measures like we did last time,” Trump told US news website Axios on Tuesday.

Trump also floated the idea of ​​sending a second aircraft carrier to Iran, a threatening signal following the U.S.’s. Bombing of three Iranian nuclear facilities June.

Iranian President Masoud Pezeshkian said on Wednesday that Iran was ready to demonstrate the peaceful nature of its nuclear program but would “not give in to excessive demands.”

“Our Iran will not yield in the face of aggression, but we will continue to fully engage in dialogue with our neighbors to establish peace and tranquility in the region,” Pezeshkian said.

Qatar emir speaks to Trump, Iran’s Larijani

Meanwhile, Ali Larijani, another senior adviser to Iran’s Supreme Leader Ayatollah Ali Khamenei, visited Qatar and met with Emir Sheikh Tamim bin Hamad Al Thani to discuss the progress of U.S. negotiations.

Larijani told Al Jazeera that discussions on Wednesday were positive, adding that Iran remained in contact with “all parties” regarding a possible second round of U.S. talks.

The Emir of Qatar also had a phone call with Trump before the meeting. Conference of United States Presidents With visiting Israeli Prime Minister Benjamin Netanyahu.

The Israeli prime minister is expected to press Trump to take a tough stance in talks with Iran, including demanding concessions on Tehran’s military arsenal such as ballistic missiles and support for regional groups such as Hezbollah.

Hassan Ahmadian, an associate professor at the University of Tehran, said Iran views its ballistic missile program as a red line because it is vital to its defense.

“There are limits to what Iran can offer,” Ahmadian told Al Jazeera. “Until now, Iranian policymakers have insisted that discussions about Iran’s defense capabilities are unacceptable. To attack a country and then expect it to hand over its primary means of defense is a ridiculous argument.”