New U.S. strategy pressures South Korea defense

U.S. Undersecretary of Defense for Policy Elbridge Colby, who recently visited South Korea, praised the country as a “model ally,” but the substance of his message was closer to an alliance invoice than a compliment.

Colby, the third-ranking official at the Pentagon, repeatedly stressed to South Korean foreign and security officials that South Korea should take the lead in defending the Korean Peninsula by strengthening its own military capabilities. He effectively reaffirmed that the primary responsibility for defense against North Korea rests with South Korea, in line with the new National Defense Strategy announced by the Donald Trump administration shortly before his trip.

A military official said that although Colby used the term “lead,” the message amounted to a call for South Korea to substantially increase defense spending and assume full responsibility for conventional deterrence against North Korea. With Colby regarded as a key Trump security strategist and a principal architect of the new strategy, his visit signals a major turning point for the 73-year South Korea-U.S. alliance, as the role of U.S. Forces Korea shifts from focusing on North Korean threats to countering China.

His remarks are widely interpreted as suggesting that U.S. Forces Korea could be reorganized around naval and air assets better suited for deterring China. Some observers have raised the possibility of withdrawing ground combat units such as the 210th Field Artillery Brigade, the only U.S. combat brigade stationed north of the Han River. If South Korea assumes primary responsibility for conventional defense against North Korea, the rationale and effectiveness of maintaining large U.S. ground forces near the Military Demarcation Line could be questioned.

There is also speculation that Stryker brigades that rotate from the U.S. mainland to South Korea could be redeployed to Japan or Guam to support missions related to countering China.

If such changes materialize, the risk of sending the wrong signal to North Korea would grow. Pyongyang could misread a chain of developments, including the restructuring of U.S. Forces Korea, faster progress on the transfer of wartime operational control, and a broader U.S. strategic shift, as a weakening of South Korea-U.S. deterrence. Colby’s comments could also be interpreted by North Korea as reduced U.S. willingness to intervene in a Korean Peninsula contingency, potentially encouraging further provocations against the South.

That is why the government and the military must devote maximum effort to readiness and to strengthening independent defense capabilities. The most urgent task is to accelerate deployment of the Korean three-axis defense system and secure an independent capacity to counter North Korea’s nuclear threat. Rapid detection, tracking, defense and strike capabilities against North Korean nuclear missiles are central pillars of credible deterrence. This requires sufficient and sustained defense investment, along with policy consistency that rises above ideology and partisan politics.

A full redesign of force structure and units that integrates advanced technologies such as artificial intelligence and drones should also follow. Highly responsive defense systems that combine unmanned surveillance and rapid strike capabilities should be established at the earliest possible stage in frontline areas, including the northwestern islands and the Demilitarized Zone.

The military can no longer rely on a troop-heavy warfighting paradigm. Gaps caused by a shrinking pool of available personnel should be quickly offset through precision strike assets, long-range firepower and unmanned combat systems, significantly strengthening asymmetric capabilities against North Korea.

A firm willingness to respond is equally essential. If the military hesitates to respond to North Korean provocations because of political calculations, the credibility of deterrence will erode and North Korea will be more likely to pursue bolder military actions. A military official said operational readiness must be reinforced so that North Korea clearly understands any provocation will be met with immediate and multiplied retaliation.

The Donald Trump administration’s new National Defense Strategy and Colby’s visit serve as a stark reminder that the South Korea-U.S. alliance is not a free insurance policy but a capability-based contract. Faced with a test of alliance burden sharing in leading defense against North Korea, the armed forces’ top priority is to secure stronger self-defense capacity without delay. Premature calls for self-reliant defense driven by pride amount to a gamble with national security.