President Yoon Suk Yeol visited a key U.S. Forces Korea wartime command bunker complex on Wednesday amid an ongoing joint military exercise, sending a warning message to North Korea over its nuclear and missile threats.

Yoon visited CP Tango, or the Command Post Theater Air Naval Ground Operations, in Seongnam, Gyeonggi, meeting with South Korean and U.S. troops to check on the progress of the 11-day Ulchi Freedom Shield (UFS) which began on Monday, according to the presidential office in a statement.

This marks the first visit by a Korean president to a wartime mountain bunker in a decade, since former President Park Geun-hye’s visit in 2013.

“Since the establishment of the South Korea-U.S. Combined Forces Command in 1978, CP Tango has served as the brain commanding the three military branches of our two countries during wartime,” Yoon was quoted as saying by presidential spokesman Lee Do-woon.

“North Korea’s nuclear weapons and missiles are the most serious threat, and its provocations, such as cyberattacks and psychological warfare, are becoming increasingly sophisticated and diversified,” Yoon said.

He said that the “overwhelming capabilities” of the alliance and joint training and drills “are the source of strength to deter and to punish North Korea immediately and decisively in case of provocation.”

Yoon said that the combined exercise “is a symbol of the ironclad South Korea-U.S. military alliance.”

He urged for a stronger response posture against North Korea’s nuclear and missile threats and ordered the preparation of a military-level response plan through the bilateral Nuclear Consultative Group (NCG) to enhance the execution capability of extended deterrence, according to his office.

Yoon also stressed that trilateral cooperation with Japan will help to “reduce the risk of provocation by North Korea and contribute to the freedom, peace and prosperity of mankind as a whole.”

In addition to South Korea and the United States, nine United Nations Command member countries, including Australia, Canada, France, New Zealand and the United Kingdom are also participating in this year’s combined exercise.

BY SARAH KIM [kim.sarah@joongang.co.kr]