Defense Secretary James Mattis James Norman MattisBiden courts veterans amid fallout from Trump military controversies Trump says he wanted to take out Syria's Assad but Mattis opposed it Gary Cohn: 'I haven't made up my mind' on vote for president in November MORE issued a stern warning during his visit to the Korean Demilitarized Zone (DMZ) on Friday, saying that Pyongyang continues to “threaten others with catastrophe" through building a nuclear weapons arsenal, but emphasized that the U.S. is not angling for war.

Mattis referred to North Korea as “an oppressive regime that shackles its people, denying their freedom, their welfare and their human dignity in pursuit of nuclear weapons and their means of delivery in order to threaten others with catastrophe," during his visit to the DMZ with South Korean Defense Minister Song Young-moo.

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"North Korea provocations continue to threaten regional and world peace, and despite the unanimous condemnation by the United Nations Security Council, they still proceed," he said. "As the U.S. secretary of State has made clear, our goal is not war, but rather the complete verifiable and irreversible denuclearization of the Korean peninsula."

Despite the tough rhetoric toward North Korea, Mattis stressed to U.S. troops stationed in Seoul that the U.S. was not angling for war.

"We're doing everything we can to solve this diplomatically, everything we can. But ultimately our diplomats have to be backed up by strong soldiers, sailors, airmen and Marines," he said

Mattis's visit comes before President Trump embarks on a 12-day trip to Asia on Nov. 3.

Trump appeared to raise the possibility of a potential presidential visit to the zone at the White House on Wednesday.

“Well, I'd rather not say, but you'll be surprised,” he said.

Tensions between Washington and Pyongyang have reached a boiling point in recent months, triggered by North Korea's launch of several intercontinental ballistic missiles.

Trump has referred to the country's leader Kim Jong Un as "little rocket man," while Kim has ripped Trump as a "mentally deranged dotard."