Defense Secretary James Mattis addressed North Korea’s threat to the world on Thursday during a visit to the Demilitarized Zone, calling for “verifiable and irreversible denuclearization” in the region.

Mattis addressed South Korean troops and the media, reiterating Secretary of State Rex Tillerson’s message by saying “our goal is not war,” CNN reported.

“As the U.S. Secretary of State Tillerson has made clear, our goal is not war, yet rather the complete verifiable and irreversible denuclearization of the Korean peninsula,” Mattis said.

The defense secretary’ trip to the region comes ahead of President Donald Trump’s visit to Asia next month and as tension grows between North Korea and the United States and its allies. The United Nations has repeatedly condemned North Korea’s illicit nuclear program and defiance of international calls to stand down.