President Donald Trump warned North Korea on Wednesday, "do not underestimate us, and do not try us," but the country's officials were unimpressed, CNN reports.

"We will not allow American cities to be threatened with destruction," Trump said in a speech before the National Assembly in Seoul. "We will not be intimidated. And we will not let the worst atrocities in history be repeated here, on this ground we fought and died to secure.

"The world cannot tolerate the menace of a rogue regime that threatens it with nuclear devastation. All responsible nations must join forces to isolate the brutal regime of North Korea — to deny it any form of support, supply, or acceptance."

A North Korean official told CNN later, "we don't care about what that mad dog may utter because we've already heard enough."

The officials add they are more concerned by the actions of the U.S. military than of Trump's words, pointing to three American aircraft carriers and one submarine off the coast of the country.

"The United States is threatening us with nuclear aircraft carriers and strategic bombers," the officials said. "They are challenging us with the most vicious and demeaning provocations, but we will counter those threats by bolstering the power of justice in order to take out the root cause of aggression and war."