War Secretary Pete Hegseth visited the demilitarized zone between North and South Korea on Monday, as part of his trip to South Korea for talks.

Hegseth and South Korean Defense Minister Ahn Gyu-back toured key military sites along the heavily fortified border with North Korea on Monday, underscoring the allies' defense cooperation amid rising regional tensions.

The two received a briefing at Observation Post Ouellette near the Demilitarized Zone, a symbolic site visited by President Donald Trump in 2019, before traveling to the Panmunjom border village where the Korean War armistice was signed.

Seoul's Defense Ministry said the visit "reaffirmed the firm combined defense posture and close coordination" between the allies.

Separately, the nations' Joint Chiefs of Staff leaders oversaw the first-ever combined formation flight of U.S. and South Korean F-16s above a major U.S. base in Pyeongtaek, a display of what officials described as the alliance's "ironclad" readiness.

Hegseth and Ahn are scheduled to meet again Tuesday for annual defense talks in Seoul, expected to focus on increased South Korean defense spending and the long-delayed transfer of wartime operational control.

Hegseth's visit follows Trump's recent trip to South Korea for meetings with President Lee Jae Myung and Chinese President Xi Jinping, during which Trump announced plans to share U.S. nuclear submarine technology with Seoul and praised $350 billion in new South Korean investments aimed at easing U.S. trade tensions.