Contesting the rimlands: Ukraine, Iran, Korea?
As the most exposed and valuable maritime wedge on the Asian continent, South Korea may be where that contest will sharpen next - unless Seoul takes control of its own destiny.
The wars in Ukraine and Iran are routinely seen as separate—one a grinding territorial conflict in Europe, the other a slow-burning confrontation in the Middle East.
This framing is neat, even comforting. Some like to imagine that it all could have been avoided if it weren’t for Trump or Netanyahu’s influence. They like to think that each conflict can be managed on its own terms. This is wrong.
Ukraine and Iran are not isolated events. They are connected expressions of technological change and geopolitical struggle—one driven by the rising strength of continental powers and the relative decline of maritime power, playing out across the rimlands where they collide.
Nearly a century ago, Nicholas J. Spykman argued that power is not decided in the continental interior, but along the more densely populated, economically vital edges of Eurasia—the zones where land and sea power meet. These rimlands are not peripheral. They are decisive. Control them, and the balance of the entire system shifts.
For much of the modern era, this contest along the rimlands favored maritime powers. Sea control allowed them to move forces at scale, supply distant positions, and project power onto the continent’s edges with relative freedom. The rimlands were accessible, penetrable, and—crucially—contestable on maritime terms.
Over the past two decades, that balance has shifted. Advances in precision strike, layered air defence, missile technology, and surveillance have transformed these same zones into hardened barriers. What were once gateways have become denial belts. Continental powers can now extend their reach outward, holding coastal approaches at risk and complicating any attempt at external intervention. The rimlands remain decisive—but they no longer favor those who approach from the sea.
This shift is already visible in Ukraine. What might once have been a contest decided by external reinforcement and maritime access has instead become a grinding struggle shaped by proximity and denial. Ukraine sits at the fault line between continental Russia and the maritime-oriented European order, but the terms of that contest have changed.
Russia’s ability to project power from the land—through missiles, air defense, and depth—has complicated Western efforts to decisively shape the battlefield. What was once a rimland accessible to maritime influence has become a contested denial zone. Ukraine is no longer simply a hinge between systems; it is a demonstration of how the European rimland is tilting toward continental advantage.
The same dynamic is unfolding further south in Iran. The Persian Gulf was long treated as a maritime domain—open to naval dominance and external control. That assumption no longer holds.
Iran’s growing capacity to threaten shipping, target regional bases, and extend its reach through missiles and proxies has transformed the southern rimland into a space of persistent risk and constrained access. Its geographic position—linking Central Asia, the Caucasus, and the Indian Ocean—remains critical, but it is now reinforced by an ability to deny rather than simply endure. The result is a strategic environment in which maritime power can no longer operate with impunity, and where continental influence increasingly defines the terms of engagement.
Taken together, these conflicts reveal a pattern. They occur along the margins of the continent, in zones where competing forms of power collide. They are not aberrations. They are structural.
And this is what makes Korea so consequential.
The Korean Peninsula is not simply another point along the rimland. It is one of its most volatile and strategically loaded positions. Unlike Ukraine or Iran, Korea is not a broad corridor or a contested hinterland. It is a narrow, compressed space—a wedge.
Projecting out from the Asian continent, Korea functions as a maritime foothold embedded directly against continental power. It is, in effect, a forward operating position for maritime states—most notably the United States—placed at the very edge of China’s strategic environment. This makes it invaluable. From Korea, maritime power can monitor, constrain, and if necessary project force into the continental sphere. It is not simply adjacent to China; it is pressed up against it.
This is precisely why Korea is so volatile. As continental powers accrue advantages—through geography, industrial depth, and increasingly sophisticated denial capabilities—the value of secure, forward positions along the rimland rises sharply. Korea offers exactly that: a defensible, highly developed, and deeply integrated platform from which to offset continental strength.
But that same value makes it intolerable from the continental perspective.
To a rising continental power, the presence of a maritime-aligned wedge on its doorstep is not a neutral fact. It is a constraint—a permanent intrusion into its strategic depth. The logic that drives contestation in Ukraine and Iran applies here with greater intensity. If the European and Middle Eastern rimlands are about influence and access, Korea is about proximity and penetration.
It is the difference between contesting the edges of a system and confronting an embedded position within it.
This is why Korea cannot remain a passive space. The structural pressures that have already produced conflict elsewhere along the rimland are present here in concentrated form. A maritime state seeks to maintain a secure forward position. A continental power seeks to remove or neutralise it. Neither objective can be fully realised without altering the status quo.
The result is not necessarily immediate war, but it is persistent instability—military signalling, alliance tightening, technological competition, and periodic crises that test the boundaries of control. Over time, these pressures accumulate.
What Ukraine shows is that rimland conflicts cannot be deferred; they eventually erupt. What Israeli/US action in Iran shows is that maritime powers are willing to see territories neutralized rather than see continental power expand. As Chinese and Russian power rises and American maritime dominance erodes, these dynamics intensify.
The wars we see today are not random. They are sequential contests along the same geographic belt. The system is not breaking apart; it is reorganizing along its most sensitive edges.
Ukraine is one front. Iran is another.
As the most exposed and valuable maritime wedge on the Asian continent, South Korea may be where that contest will sharpen next - unless Seoul takes control of its own destiny.