Will the U.S. Bring Tactical Nukes Into South Korea's Defense? Review Underway of 'Usable Nuclear' Strategy

[Financial News] The United States Department of Defense is reviewing a new nuclear strategy that would expand the role of short-range tactical nuclear weapons in defending allies during regional conflicts with China and Russia. The move reflects the view that long-range strategic nuclear threats alone, which could destroy major cities and national infrastructure, may not be enough to convince adversaries that the United States would actually use nuclear weapons.
If the new strategy is adopted, it could bring significant changes to U.S. extended deterrence for allies such as South Korea and Japan, which are close to China and Russia. While some say the U.S. nuclear umbrella would gain more concrete and realistic response options, concerns are also expected to grow that it could lower the threshold for nuclear use.
NBC News reported on the 5th, citing multiple sources, that a new nuclear strategy draft overseen by U.S. Deputy Defense Secretary for Policy Elbridge Colby includes a stronger emphasis on short-range tactical nuclear weapons.
The existing U.S. nuclear strategy has emphasized the ability to destroy an enemy's homeland and nuclear forces with long-range strategic nuclear assets such as intercontinental ballistic missiles (ICBMs), strategic bombers, and submarine-launched ballistic missiles (SLBMs). The new concept focuses not only on such large-scale retaliatory options, but also on expanding choices to include smaller nuclear weapons that can target limited sites such as battlefields and military bases.
A senior U.S. Department of Defense official told NBC News, "We believe credible nuclear options are necessary," explaining that deterrence is strengthened when President Donald Trump is given a range of response options that could actually be used.
The key is to make China and Russia believe that the United States could use nuclear weapons on behalf of its allies even if the U.S. homeland has not been directly attacked.
At present, U.S. extended deterrence is based on the promise that if allies such as South Korea and Japan come under nuclear attack, Washington will respond as if the U.S. homeland itself had been attacked. However, the so-called issue of the "credibility of extended deterrence" has persisted, as questions remain over whether the United States would really risk retaliatory strikes on its own cities by using large-scale strategic nuclear weapons in response to a limited nuclear attack by China or Russia.
Colby's team argues that having small tactical nuclear weapons could actually help deter nuclear use, since they would allow an immediate response in a regional conflict without escalating into a full-scale nuclear war.
A U.S. Department of Defense official said, "For extended deterrence to be credible, it must provide nuclear capabilities that the political leadership of the country in question would judge to be actually usable." He added that if only extreme options such as strategic nuclear retaliation are left on the table, adversaries may not believe U.S. nuclear threats, which would ultimately weaken deterrence.
Colby has long argued for the need for low-yield tactical nuclear weapons that can strike limited targets on the battlefield, rather than strategic nuclear weapons designed to destroy entire capitals or major cities. His logic is that nuclear weapons should not be left as symbolic tools that cannot be used, but should instead be made into options that can be employed in real military operations.
He is expected to attend the U.S. Strategic Command Deterrence Symposium, which will be held in Omaha, Nebraska, on the 5th and 6th, where he will discuss the National Defense Strategy (NDS) and future nuclear strategy. U.S. Strategic Command is the unified combatant command responsible for U.S. nuclear forces and nuclear deterrence operations.
The new strategy is likely to have a direct impact on the security of South Korea and Japan. That is because the United States could consider tactical nuclear weapons as a key response option in the event of a Taiwan Strait conflict with China or a contingency on the Korean Peninsula.
In particular, if the United States expands low-yield nuclear forces that can be used quickly in the region, in addition to long-range strategic nuclear weapons, it could also affect discussions in South Korea about redeploying tactical nuclear weapons or pursuing nuclear sharing. However, the NBC report concerns only an internal Pentagon strategy draft and does not mean that a decision has been made on deploying tactical nuclear weapons to the Korean Peninsula.
Criticism is also strong. Tactical nuclear weapons are less powerful than strategic nuclear weapons and have a more limited attack range, which may make it easier for political leaders to decide to use them. Critics say this could increase the likelihood of nuclear use and raise the risk that a conventional war could escalate into a nuclear war.
A senior figure in the U.S. Congress criticized the plan as an approach that runs counter to the Trump administration's emphasis on strengthening nuclear deterrence. He argued that overreliance on limited tactical nuclear weapons could lead the president to choose a restrained option even in situations where long-range strategic nuclear weapons would need to be used.
Debate over U.S. nuclear strategy is intensifying as the last remaining U.S.-Russia strategic arms control framework weakens and China rapidly expands its nuclear forces. Russia possesses a large number of tactical nuclear weapons that can be used not only as strategic nuclear assets but also in regional conflicts, while China is also expanding its warheads and delivery systems.

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