This article is entirely my personal conjecture. However, rather than just scribbling pure speculation, I’ve tried to align it with geopolitical logic and actual movements as much as possible.
Who Does the US Really Consider an Ally?
The ROK-US alliance is said to be firm. However, looking at recent developments, it’s questionable whether the US will truly stand by South Korea until the end. While they outwardly claim solidarity, within the actual strategic framework, South Korea no longer holds the important position it once did. For example, at the 2023 US-South Korea summit, the US promised to expand its nuclear umbrella, but behind the scenes, it’s concentrating more strategic assets on containing China and defending Taiwan. Additionally, the US’s tough stance during negotiations over burden-sharing costs for US forces in Korea signals that they prioritize cost efficiency and strategic realignment over maintaining the alliance. The Korean Peninsula may no longer be a “strategic core” for the US. America’s real interest has already shifted to Taiwan, and Korea is increasingly becoming a “dispensable card.”
This might sound absurd. But let’s examine it dispassionately: where is the US currently concentrating its resources, and with whom is it increasing military connections?
Cold War Era: The Korean Peninsula Was an Advanced Base for Containing the Soviet Union
Now as before, the core of US defense strategy remains the same: “Preventing enemy countries from approaching seas adjacent to the US mainland.” However, since the US borders the Pacific Ocean to the west and the Atlantic Ocean to the east, an unreasonably large military force would be needed to defend these vast oceans entirely. Additionally, due to the scientists Germany spirited away competitively by the US and Soviet Union during the Nazi collapse, missile technology progressively advanced. By the height of the Cold War, it became possible to place the entire US mainland within missile range simply by reaching somewhere in the middle of the Atlantic or Pacific with submarines carrying long-range ballistic missiles. Consequently, the strategy the US adopted was to establish defense lines right in front of enemy coastlines, preventing them from even accessing the open seas.
During the Cold War, the US was confronting the Soviet Union on both European and Asian fronts. In Europe, it stood against the USSR through NATO, while in Asia, it built a “Pacific defense line” using Japan, Korea, and Taiwan as strongholds. The Korean Peninsula was particularly geographically adjacent to China and the Soviet Union, and served as a forward base that could directly block advances toward Manchuria or Vladivostok. Furthermore, since Kim Il-sung’s North Korean regime was hostile to China and pro-Soviet, it wasn’t impossible for the Soviet Union to attempt Pacific access using North Korea as an intermediary. This made South Korea’s geopolitical value even more important.
America’s direct intervention in the Korean War wasn’t simply an ideological issue. If the Soviet Union completely controlled the Korean Peninsula, the balance in the Pacific could collapse. There was significant strategic concern that if the Soviet navy advanced to the Pacific through the East Sea, it could pose a direct threat to Japan, Hawaii, and ultimately the US mainland. In fact, the US Department of Defense in the 1950s and 60s identified blocking the Vladivostok fleet’s southward movement as a key strategic task, and documents like “NSC 68” mentioned securing the Asian front as essential to containing the Soviet Union.
Especially since the Soviet Union (and present-day Russia as well) has its center of gravity skewed toward Europe due to Moscow’s location. Therefore, from America’s perspective, it was cheapest, at that time, to gather European countries to create NATO and prevent the Soviet Union from accessing the Baltic/Black Seas, while deploying US forces in Japan and Korea to block the Far East, where Soviet power was relatively difficult to project. Thanks to this, Europe, which had been engulfed in flames for nearly 30 years of world wars, could redirect defense costs to economic development by relying on the US for defense. The problem is that now that Europe has gone beyond merely being comfortable to becoming prosperous, they still want to reap benefits, which is why Trump rages and hurls insults about Europe being parasitic on the US.
In any case, due to these circumstances, Korea at that time wasn’t simply an “ally” but a “frontline that had to be defended.” Back then, Korea was a region worth investing in from the US perspective. However, this situation changed dramatically with the collapse of the Soviet Union in 1991.
Changing Times: China Containment Strategy and the First Island Chain
The world has changed. The Soviet Union collapsed, and Russia is no longer America’s number one adversary. The entity that now fully occupies America’s mind is China.
China is challenging the US comprehensively in economic power, military strength, cyber capabilities, artificial intelligence, semiconductors, and maritime hegemony. In particular, the militarization of the South China Sea, military threats against Taiwan, and the expansion of global influence through the Belt and Road Initiative are strategic provocations the US cannot ignore.
America’s strategy to contain China is simple: maritime blockade, specifically restricting activities along the First Island Chain that China itself claims. (※ Although the First Island Chain was originally a Chinese maritime expansion strategy concept, the US also employs a parallel strategy to contain Chinese naval expansion based on this line.)
The part marked as “Inner Island chain” in the photo is the First Island Chain. (Source: ASPI The Strategist)
This island chain connects Japan’s mainland with Okinawa, Taiwan, and the Philippines. Visually, it forms an arch-shaped curve from Northeast Asia to the southwest, surrounding the Chinese mainland, functioning like a strategic “wall” separating the Pacific and China. If this line were marked on a map image, it would be much easier to understand why the US is focusing on this line. The key is preventing the Chinese navy from breaking through this line. Simply put, it’s a strategy of locking China in to prevent it from accessing the Pacific.
Strengthening US-Japan and US-Taiwan Cooperation and Korea’s Marginalization
This has made Japan and Taiwan increasingly important. Japan has effectively transformed its Self-Defense Forces into a US-like military, revising security legislation, and has pledged to increase defense spending to 2% of GDP. The US-Japan alliance now functions not as a “symbolic alliance” but as a practical operational unit.
The same goes for Taiwan. It is increasing its security dependence on the US using semiconductors as leverage, and is strengthening mandatory military service and expanding military training to raise domestic defense awareness. The US is even elevating Taiwan to essentially ally status through not just arms sales but also joint training with Taiwanese forces, high-level meetings, and unofficial troop deployments.
But what about South Korea? It is located outside this line, and its strategic value has relatively diminished. Simultaneously, economic ties with China are difficult to sever, and domestic public opinion wavers between anti-American and pro-Chinese sentiments.
Korea Becomes a ‘Burdensome Ally’
In recent years, the US has openly strengthened military and intelligence cooperation with Taiwan. High-ranking US military generals have openly visited Taiwan and conducted joint simulations. There have even been reports that US electronic warfare assets participated in major military exercises in Taiwan.
All these actions essentially disregard the existing diplomatic agreement of “not recognizing Taiwan as a country.” The US is elevating Taiwan to the level of a ‘substantive ally’ to this extent.
But what about South Korea? US forces still remain stationed in Korea, but anti-American sentiment persists within Korea, and economic entanglement with China is complex. On issues like THAAD deployment, semiconductor supply chains, and Taiwan Strait statements, Korea consistently takes an ambiguous position. For example, during the THAAD deployment, it hesitated due to concerns about Chinese retaliation; on semiconductor supply chains, it failed to take a clear position despite US pressure; and regarding the Taiwan Strait, statements were limited to diplomatic remarks attempting to balance between the US and China.
From the US perspective, Korea is no longer an ‘obedient ally.’ There’s an atmosphere of seeing Korea not so much as an ally but as ‘a country that cooperates but cannot be trusted.’
Moreover, the fact that anti-American sentiment fluctuates greatly depending on Korea’s political landscape is also a burden for the US. With each change in administration, the diplomatic stance toward China/US changes dramatically, making it difficult for the US to establish a consistent strategy. This unpredictability is a fatal weakness for an ally.
Korea Being Pushed Outside Strategic Priorities
From the US perspective, strengthening Japan and Taiwan to maintain the maritime defense line is far more practical. Japan has gone so far as to revise its constitution to side with the US, and Taiwan is courting the US to become its forward base. Meanwhile, Korea is just watching cautiously from the middle, with significant political instability. Even within Korea, claims like “don’t provoke China” and “maintain neutrality on the Taiwan issue” are openly voiced. From the US perspective, this means Korea cannot clearly take sides in case of war.
If the US is seriously preparing for military conflict with China, the main defense line will be the ‘Japan-Taiwan-Philippines’ line. Korea is increasingly diverging from this, and will likely become a ‘card not chosen.’ If this scenario materializes, the US will not include Korea in its defense line. Instead, it will concentrate that energy on Taiwan, Japan, and countries around the South China Sea. From the US perspective, such gray zones represent strategic uncertainty, creating a significant burden as they can’t expect quick responses or definite cooperation in emergencies. Korea is likely to become an ambiguous gray area that “might or might not” support the US.
There’s a concept called the ‘Thucydides Trap.’ It suggests that when a rising power challenges the hegemony of an existing power, war inevitably occurs in the process. Once hegemony is gained, no one wants to relinquish it. The US toppled the Soviet Union through intense brinkmanship, then knocked down Japan, which had grown threatening, through the Plaza Accord. Now China has risen to challenge the US. The US-China conflict is an inevitable destined confrontation that will certainly arrive someday, but how prepared has our country been for it? Reflecting on this makes me feel rather somber.