U.S. Deputy Secretary of Defense for Policy Elbridge Colby exits the venue after concluding discussions on diplomatic and security issues with Foreign Minister Cho Hyun at the Four Seasons Hotel in Jongno-gu, Seoul, on Monday morning 2026.1.26 / News1

Following the recent announcement of the U.S. National Defense Strategy (NDS), Deputy Secretary of Defense Elbridge Colby visited South Korea for a series of high-level meetings with foreign and security officials. Analysts on Tuesday suggested that this official shift in U.S. defense strategy could impact the upcoming U.S.-South Korea joint military exercises in March.

On Monday, Colby met with Foreign Minister Cho Hyun, National Security Office Director Wi Sung-lac, and Defense Minister Ahn Gyu-back. They discussed the Korean Peninsula security situation, South Korea's nuclear-powered submarine acquisition, wartime operational control transfer, and other alliance issues. After arriving post-NDS announcement, Colby repeatedly emphasized South Korea's status as a model ally and reportedly discussed aligned security responses within the NDS framework.

The new NDS outlines that South Korea will take the lead in responding to North Korea's conventional threats, while the U.S. role shifts to more important but limited support. This codifies the Donald Trump administration's emphasis on increased allied contributions to security matters.

Notably, the NDS identifies the simultaneity problem as central to the U.S. security environment. This concept suggests that potential adversaries like China, Russia, Iran, and North Korea could simultaneously threaten the U.S. across multiple theaters, necessitating increased allied contributions.

Colby, who spearheaded the NDS drafting, has long advocated for this security self-reliance approach, even before his appointment as Deputy Secretary last April. As a key Trump security strategist, Colby likely shaped the President's alliance views.

In a Sejong Institute speech, Colby discussed a denial defense line based on the First Island Chain - the U.S. containment strategy against China linking Japan's Kyushu, Okinawa, Taiwan, and the Philippines. He emphasized building a military posture that makes crossing this line impossible, escalation unattractive, and war irrational. This includes modernizing flexible, distributed capabilities across Japan, the Philippines, Korea, and the region.

This strategy aims to leverage regional forces to counter Chinese military expansion, particularly regarding Taiwan. For the Korean Peninsula, this suggests a potential shift in U.S. forces' role from North Korean deterrence to Chinese containment.

Elbridge Colby, U.S. Deputy Secretary of Defense for Policy, speaks during his visit to Camp Humphreys, a U.S. military base in Pyeongtaek, Gyeonggi Province, on Monday afternoon &#40;Capture from U.S. Forces Korea Commander General Xavier Brunson&#39;s X&#41; 2026.1.26 / News1

U.S.-South Korea Exercises: Pivot to China? Diplomatic Challenges Loom

Colby's visit immediately following the NDS release signals rapid implementation of the U.S. alliance modernization plan. The upcoming annual U.S.-South Korea military exercises may serve as the first indicator of this shift.

Experts speculate that Colby's visit could herald a transformation in joint exercises. Rather than focusing solely on North Korean invasion scenarios, training may now incorporate the NDS simultaneity problem, potentially including Chinese actions against Taiwan. Some analysts predict scenarios involving North Korean provocations aimed at drawing out U.S. forces, localized conflicts, and even Russian intervention.

While U.S.-South Korea exercises traditionally follow established operation plans (OPLANs), the U.S. often introduces new contingencies based on evolving threats. South Korea could resist a complete pivot to China-focused exercises, but may find it difficult to dismiss multiple new U.S.-proposed scenarios.

Though official statements are lacking, experts believe Colby's meetings with South Korean officials and U.S. Forces Korea Commander General Xavier Brunson at Camp Humphreys likely involved discussions on exercise modifications.

While details remain classified, incorporating China-focused elements into joint exercises could severely test South Korea's pragmatic diplomacy. China views regional discussion of Taiwan as interference in internal affairs and is unlikely to tolerate perceived threats from U.S. strategic assets deployed on the Korean Peninsula.

Du Jin-ho, director of the Korea National Strategy Institute's Eurasia Center, stated that unlike last year's exercises under the Joe Biden administration, March's drills will purely reflect Trump administration strategies. The core focus will be countering China, with scenarios testing U.S. forces' strategic flexibility in Korea, South Korean military contributions, and overall U.S.-South Korea posture within Indo-Pacific Command.

Following the recent announcement of the U.S. National Defense Strategy (NDS), Deputy Secr …

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