(Bloomberg) -- The US ambassador to the United Nations went to the demilitarized zone dividing the two Koreas, where she criticized Pyongyang for endangering peace and invited it to return to stalled nuclear disarmament talks.

Ambassador Linda Thomas-Greenfield’s trip to the buffer zone border Tuesday came after holding talks with officials in Seoul on ways to extend the role of a UN Security Council Panel of Experts that has monitored North Korea’s nuclear-weapons development for 15 years after a veto by Russia could bring the body to a halt. Her trip was the highest-profile DMZ visit by a Biden administration official since Vice President Kamala Harris went there in 2022. 

“Let me be clear, the United States harbor no hostile intent toward the DPRK. We repeatedly asked Pyongyang to reject provocation and embrace dialogue,” Thomas-Greenfield said, referring to North Korea by its formal name. She is the first sitting US ambassador to the United Nations to visit South Korea since 2016. 

She added true peace and coexistence in the peninsula were out of reach due to North Korea’s escalatory rhetoric and misguided decision making “that endanger the peace and security of the region and beyond it.” She toured the area with General Paul LaCamera, commander of the US Forces Korea, and was watched by North Korean troops from the other side of the border when she neared the UN huts that straddle the dividing line.

A portion of her trip has been to raise support for sanctions enforcement after Russia’s veto of the US-led Security Council resolution last month to extend the panel. Reports by the body of experts inform decisions on international sanctions established by the Security Council in a series of resolutions aimed at barring North Korea from developing its nuclear arms program. 

The veto came as Moscow and Pyongyang have drawn closer since President Vladimir Putin’s full-scale invasion of Ukraine. The ambassador said Russia is protecting North Korea at the Security Council and blocking efforts to hold it accountable for provocations that violate its resolutions. 

Despite Moscow’s close ties with Pyongyang, the veto marks a shift in policy at the Security Council, as it was the first time Russia flatly opposed the panel’s mandate in the 15 years since it was established.

The UN Security Council has seen growing divisions over Russia’s war on Ukraine, and what the US says is Moscow’s push to secure weapons and ammunition from Kim Jong Un’s regime for the Kremlin’s assault on its neighbor.

Moscow and Pyongyang have denied the charges despite a multitude of satellite photos released by research groups and the US showing the flow of weapons from North Korea to Russia and then to munitions dumps near the border with Ukraine.

In return for the arms, Russia is providing North Korea with food, raw materials and parts for weapons production that help Kim boost food security and further develop his weapons systems, South Korean officials have said. 

Thomas-Greenfield arrived in Seoul on Sunday for a four-day visit that will also include a meeting with North Korean defectors before heading to Japan. In Japan, the US ambassador will meet officials to discuss shared priorities at the UN and hear from family members of Japanese citizens abducted by North Korea, her office said. 

The 4-kilometer (2.5-mile) wide buffer where hundreds of thousands of troops are stationed on opposing sides of razor-wire fencing is dubbed the Cold War’s last frontier and a symbol of simmering tensions that have lasted since the end of the 1950-1953 Korean War. 

“This was really an eye-opening experience for me visiting the DMZ,” she said. “We all read about it, we’ve heard about it but seeing it up close was really, truly an experience that I will not forget.”

(Updates and recasts with visit, fresh quotes)

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