DMZ Access Battle Deepens US South Korea Tensions

At the heart of the Korean Peninsula, the demilitarized zone (DMZ) stretches some four kilometers wide, serving as a buffer between North and South Korea since the 1953 armistice that ended active combat in the Korean War. For more than seventy years, this strip of land has not only separated two rival states but has also become a symbol of unresolved conflict, international oversight, and, increasingly, a site of political tension between South Korea and its closest ally, the United States.

Recent events have brought these underlying frictions to the fore. According to Yonhap News, the U.S. Army's 5th Air Cavalry Squadron, 17th Cavalry Regiment (5-17 ACS), based at Camp Humphreys in Pyeongtaek, was deactivated on December 15, 2025. This unit, which had provided reconnaissance support to the 2nd Infantry Division since its activation in May 2022, boasted hundreds of personnel and sophisticated aviation assets, including AH-64E Apache helicopters and RQ-7B Shadow drones. The deactivation, part of a broader Army transformation initiative, has fueled speculation about a potential reduction in the 28,500-strong U.S. Forces Korea (USFK) presence—a topic that has long simmered beneath the surface of alliance discussions.

Just one day after the 5-17 ACS was stood down, the 2nd Infantry Division's Combat Aviation Brigade Medical Evacuation (CAB MEDEVAC) unit underwent restructuring, as noted in a recent Congressional Research Service report. While the Pentagon has publicly reaffirmed its commitment to South Korea’s defense, the absence of explicit language in last year's key security documents about maintaining current USFK troop levels has only intensified speculation. The Wall Street Journal reported in May 2025 on discussions about relocating roughly 4,500 troops from Korea to other Indo-Pacific locations—a claim the Pentagon swiftly denied, yet one that continues to provoke concern among South Korean officials and analysts.

Overlaying these military adjustments is a charged debate over who controls access to the DMZ—a question that strikes at the very core of South Korean sovereignty and alliance coordination. As reported by the Korea JoongAng Daily, a legislative proposal by lawmakers from South Korea’s Democratic Party seeks to grant the government authority over civilian access to the DMZ for peaceful purposes. This move would bypass the United Nations Command (UNC), which, under the 1953 Armistice Agreement, maintains strict control over all entries into the zone, whether military or civilian.

The UNC, a coalition led by the United States and comprising 18 nations, has administered the DMZ since the armistice. Article I of the agreement makes clear that “civil administration and relief activities in the DMZ which is south of the MDL shall be the responsibility of the Commander-in-Chief, United Nations Command.” For decades, entry has required approval from the UNC’s Military Armistice Commission, with 48 hours’ notice—a rule that applies even to South Korea’s highest officials.

This rigid system was thrust into the spotlight in late 2025 when Kim Hyun-jong, the first deputy director of South Korea’s National Security Office, was initially denied permission to visit the Baekma-Goji excavation site inside the DMZ, where over a 40-day period, 25 sets of Korean War remains and nearly 2,000 artifacts had been recovered. The denial sparked public outrage and was quickly framed as an affront to national sovereignty. Unification Minister Chung Dong-young voiced the sentiment widely felt in Seoul, stating that it was unacceptable for a senior security official to be barred from “our own land” in the DMZ. After public criticism mounted, the UNC reversed its decision two weeks later, granting Kim access on December 17, 2025.

This was not an isolated incident. Earlier in 2025, a planned prayer-for-peace ceremony by visiting Cardinal Lazzaro You Heung-sik had to be canceled due to procedural hurdles—the cardinal’s team had not provided the required 48-hour notice. Even during the 2007 inter-Korean summit, then-President Roh Moo-hyun needed final clearance from the UNC before crossing the military demarcation line, a reminder of just how deeply the armistice regime shapes even the most symbolic acts of reconciliation.

Proponents of the new DMZ law argue that the UNC’s control, while rooted in international law and the logic of armistice, has become overly restrictive and extends beyond its original military mandate. Yang Moo-jin, a professor at the University of North Korean Studies, told the Korean press, “The UNC’s role should be limited to military functions under the armistice.” He pointed to the Kim Hyun-jong case as an example of what he called an “overextension” and “arbitrary interpretation” of the UNC’s authority, adding, “This shows that the UNC is reacting politically, not legally—which it was never meant to do.”

Yet, the UNC and its supporters remain steadfast. In a public statement on December 17, the UNC reiterated, “DMZ access control is the inherent authority of the UNC under the armistice,” warning that any unilateral move by South Korea to override these provisions would amount to an international breach. General Xavier Brunson, commander of United States Forces Korea and the UNC, emphasized, “We’ve got to adhere to the standards put forward in the agreement,” cautioning against any attempt to “abrogate a legal document, which is the armistice.”

The South Korean Ministry of National Defense, in its review submitted to the National Assembly, acknowledged the intent behind the proposed law but insisted that any changes must occur “in close coordination with the UNC.” Meanwhile, the opposition People Power Party (PPP) has gone even further, warning that undermining UNC authority could “remove the basis for UN member states’ automatic intervention” in a crisis, thus weakening a key “safety pin” for South Korea’s security. PPP spokesman Park Sung-hoon described attempts to nullify the armistice through domestic law as a “blatant violation of the Vienna Convention,” warning it could make South Korea appear as a “rogue state” on the international stage.

These concerns are not merely academic. North Korea’s state media has repeatedly denounced the UNC as a “second, Asian version of NATO,” viewing it as a U.S.-led mechanism for multinational intervention against the North. Any move to dilute the UNC’s authority is thus watched closely not just in Seoul and Washington, but in Pyongyang as well.

Still, the push for greater autonomy continues. Unification Minister Chung Dong-young, in a joint policy briefing on December 19, reaffirmed support for the DMZ law, citing the recent incidents as evidence of the need for change. “That is our reality,” he said, underscoring the importance of legal authority to guarantee peaceful access.

The debate over the DMZ law and the recent military restructuring are reminders of the delicate balance that defines the U.S.-South Korea alliance. As both sides navigate evolving security challenges, the question of who controls the DMZ—and by extension, the peninsula’s future—remains as pressing, and as unresolved, as ever.