Communist dictator Kim Jong Un reacted to President Donald J. Trump’s warning to North Korea not to underestimate the West with fiery rhetoric of his own, demanding that the U.S. oust its president.

“The U.S. must oust the lunatic old man from power and withdraw the hostile policy towards [North Korea] at once in order to get rid of the abyss of doom,” according to a statement from the hermit kingdom, the state-run Korean Central News Agency said Wednesday. “The U.S. had better make a decisive choice…if it does not want a horrible nuclear disaster and tragic doom.”

Speaking in front of South Korea’s National Assembly Wednesday morning, President Trump made a speech aimed directly at the North Korean dictator. “Today, I hope I speak not only for our countries but for all civilized nations when I say to the North: Do not underestimate us. And do not try us,” Trump warned. “The weapons you are acquiring are not making you safer, they are putting your regime in grave danger. We will defend our common security, our shared prosperity, and our sacred liberty.”

He added, “The world cannot tolerate the menace of a rogue regime that threatens with nuclear devastation.”

The speech in South Korea comes amid a 13-day trip to Asia that has already seen the president visit Japan and South Korea, with stops in China, Vietnam, and the Philippines still on the calendar. Trump is planning to meet with Vladimir Putin when the two are in Vietnam.

During his speech, Trump described North Korea as a bleak country where citizens bribe government officials in order to leave the country, and poverty and desperation thrive instead of prosperity.

“North Korea is not the paradise your grandfather envisioned. It is a hell that no person deserves,” Trump said.

The message came hours after Trump attempted to make a surprise visit to the Demilitarized Zone, the border separating North and South Korea, with South Korean President Moon Jae-in. But heavy fog prevented Trump’s helicopter from safely landing in the area, according to a Fox News report.

“I think he’s pretty frustrated,” White House press secretary Sarah Huckabee Sanders said of the president. “It was obviously something he wanted to do.”

Trump headed to China on Wednesday for a two-day visit, which is expected to be dominated by talks about the growing nuclear crisis in the Korean peninsula. A day before he arrived in Beijing, Chinese officials ordered tour operators to halt trips to North Korean capital Pyongyang, sources told Reuters.

“It was very unexpected, we had no idea this was going to happen until we received the notification [Tuesday],” a Chinese tour operator told Reuters. “This is devastating news for us.”