Speaking in front of South Korea’s National Assembly Wednesday morning, President Trump warned North Korea: "Do not underestimate us."
"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 said. "We will defend our common security, our shared prosperity, and our sacred liberty," the president said to cheers.
"We will not allow American cities to be threatened with destruction," he continued. "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 so hard to secure."
The comments contrasted remarks the president made earlier in the week, in which he appeared open to possible talks with North Korean leader Kim Jong Un.
During a news conference with South Korean President Moon Jae-in on Tuesday, Trump argued that "it makes sense for North Korea to come to the table and make a deal that is good for the people of North Korea and for the world."
"I do see certain movement," Trump said.
But a day earlier, while in Tokyo, the president argued that "the era of strategic patience" with North Korea was finished and defended his previous rhetoric regarding the country.
That tone matched his speech on Wednesday.
"The world cannot tolerate the menace of a rogue regime that threatens with nuclear devastation," Trump argued, while advocating for "peace through strength."
"All responsible nations must join forces to isolate the brutal regime of North Korea," he said.
"It is our responsibility and our duty to confront this danger together - because the longer we wait, the greater the danger grows, and the fewer the options become," he continued. "And to those nations that choose to ignore this threat or, worse still, to enable it: The weight of this crisis is on your conscience."
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 docket.
The Associated Press contributed to this report.