North Korea again threatened to cancel its planned summit with President Donald Trump next month, saying it was ready for a “nuclear-to-nuclear showdown” if the U.S. didn’t change its approach to the disarmament talks.

A top North Korean diplomat issued the warning Thursday in response to suggestions from the Trump administration that Kim Jong Un risked the fate of toppled Libyan dictator Moammar Qaddafi if he didn’t make a deal. The official specifically criticized remarks this week by Vice President Mike Pence, who was echoing earlier comments by Trump.

“I cannot suppress my surprise at such ignorant and stupid remarks gushing out from the mouth of the U.S. vice president,” Choe Son Hui, vice-minister of foreign affairs said, according to a statement released Thursday by the state-run Korean Central News Agency.

“We will neither beg the U.S. for dialogue nor take the trouble to persuade them if they do not want to sit together with us,” Choe said. “Whether the U.S. will meet us at a meeting room or encounter us at nuclear-to-nuclear showdown is entirely dependent upon the decision and behavior of the United States.”

‘Credible Steps’

Trump has cast doubt as to whether the first-of-its-kind summit between a U.S. President and North Korean leader will take place as planned on June 12 in Singapore. Differences have emerged between the two sides over the pace and scope of “denuclearization,” with the U.S. advocating a rapid, unilateral approach while North Korea seeks a phased process of exchanges and concessions.

North Korea’s latest warning came despite Trump administration efforts to soften its stance in advance of the summit, with the president saying Tuesday he wasn’t committed to an “all in one” approach. U.S. Secretary of State Mike Pompeo also eased off U.S. demands that North Korea give up its nuclear weapons immediately, saying instead that the Trump administration wants Kim Jong Un’s regime to take “credible steps” toward that goal.

North Korea had threatened to cancel the summit last week, citing U.S. National Security Adviser John Bolton’s remarks that the regime could follow a “Libya model” of arms control. While arms control advocates cite Qaddafi’s 2011 decision to give up his weapons of mass destruction program in exchange for an easing of sanctions as a success, North Korea views his subsequent death at the hands of NATO-backed rebels as a cautionary tale.

“As the president made clear, this will only end like the Libya model ended if Kim Jong Un doesn’t make a deal,” Pence told Fox News on Monday. “The United States of America under his leadership is not going to tolerate the regime possessing nuclear weapons and ballistic missiles that threaten the United States and our allies.”

Pence had been paraphrasing similar remarks by Trump saying the Libya comparison would be accurate if Kim balked at negotiations. “That model would take place if we don’t make a deal, most likely,” Trump said.