Iran's security chief Ali Larijani on Sunday said that US President Donald Trump "will pay" the price for killing supreme leader Ayatollah Ali Khamenei. The US and Israel launched strikes on Iran on February 28, killing its 86-year-old supreme leader and triggering a war in the Middle East. "We will relentlessly avenge the blood of our leader and our people. Trump must pay and will pay," Larijani, a close aide of Khamenei, posted on X on Sunday. Trump dismissed the threats and said he doesn't know Larijani. "I have no idea what he's talking about, who he is. I couldn't care less," he told CBS News, adding that Larijani has "already been defeated." He also reiterated that the American strikes will continue on Iran and demanded an "unconditional surrender" from Tehran.