The United States has signalled a significant shift in its approach to deterring a nuclear-armed North Korea, indicating it will play a “more limited” role and place greater responsibility on South Korea to take the lead in defending the Korean Peninsula. The change, outlined in a newly released Pentagon policy document, is likely to spark debate in Seoul over the future balance of the US–South Korea alliance.
The new National Defense Strategy, published on Friday, states that South Korea is now capable of assuming “primary responsibility” for deterring North Korea, with the United States providing critical but reduced support. The document argues that this recalibration aligns with Washington’s broader strategic priorities and reflects South Korea’s growing military capabilities.
“South Korea is capable of taking primary responsibility for deterring North Korea with critical but more limited US support,” the strategy said. “This shift in the balance of responsibility is consistent with America’s interest in updating US force posture on the Korean Peninsula.”
The policy shift comes at a time of heightened tensions on the peninsula. Earlier this month, North Korean leader Kim Jong Un approved the launch of multiple ballistic missiles toward the country’s eastern waters, a move widely seen as a signal of defiance toward Washington and its allies. Pyongyang has continued to accelerate its weapons development, including nuclear-capable missiles that can potentially reach the US mainland.
South Korea currently hosts about 28,500 US troops, stationed under a decades-old alliance formed after the Korean War. The presence of American forces has long been viewed as a cornerstone of deterrence against North Korea. However, successive US administrations have increasingly questioned whether the current posture best serves America’s evolving global interests.
In recent years, US officials have suggested making American forces in South Korea more flexible, allowing them to operate beyond the peninsula if required. Such flexibility would enable Washington to respond to a wider range of regional contingencies, including tensions over Taiwan and China’s expanding military influence across the Indo-Pacific.
While South Korea has traditionally resisted any move that could weaken the US security guarantee, it has steadily expanded its own military strength over the past two decades. Seoul has invested heavily in advanced fighter jets, missile defence systems, submarines, and indigenous weapons production. For 2026, South Korea increased its defence budget by 7.5 per cent, underscoring its intent to play a larger role in its own security.
With an active-duty force of roughly 450,000 personnel, South Korea has also set a long-term goal of assuming wartime operational control of combined US–South Korean forces, a responsibility currently held by an American general. The transition, discussed for years, has been delayed amid concerns about North Korea’s nuclear threat, but remains a key objective for Seoul.
During a visit to Seoul last November, US Defense Secretary Pete Hegseth praised South Korea’s plans to further increase military spending, calling the country a “model ally” that is taking its defence obligations seriously. His comments reflected a broader US push for allies to shoulder more of the burden in maintaining regional stability.
The 25-page National Defense Strategy makes clear that defending the US homeland is the Pentagon’s top priority. In the Indo-Pacific, it says, Washington’s focus is on ensuring China cannot dominate the United States or its allies. The document emphasises competition rather than confrontation, arguing that outright conflict with Beijing is neither inevitable nor desirable.
“This does not require regime change or some other existential struggle,” the strategy said. “Rather, a decent peace, on terms favourable to Americans but that China can also accept and live under, is possible.”
Notably, the document did not mention Taiwan by name, despite ongoing concerns over cross-strait tensions. China claims democratically governed Taiwan as its own territory and has not ruled out using force to bring the island under its control. Taiwan rejects Beijing’s sovereignty claims, insisting that its future can only be decided by its people.
On the diplomatic front, Washington has renewed calls for dialogue with Pyongyang, though progress remains elusive. Former US president Donald Trump met Kim Jong Un three times during his first term in office, breaking decades of precedent, but the talks failed to produce a lasting agreement. North Korea has so far not directly responded to recent US overtures.
During a recent visit to the United States, South Korean Prime Minister Kim Min-seok discussed North Korea policy with US Vice-President JD Vance. According to Yonhap News Agency, Mr Kim suggested that Mr Trump consider appointing a special envoy to Pyongyang to restart negotiations and reduce tensions.
The Korean War ended in 1953 with an armistice rather than a peace treaty, leaving the peninsula technically still at war. North and South Korea remain divided by the heavily fortified Demilitarised Zone, one of the most militarised borders in the world.
As Washington reassesses its global military posture, the evolving division of responsibility on the Korean Peninsula is likely to become a central issue for the alliance. While US officials frame the shift as recognition of South Korea’s growing strength, concerns persist in Seoul that a reduced American role could embolden Pyongyang at a volatile moment in regional security.
