Many people assume that when a country keeps reclaiming the sea to create new land, its maritime territory automatically expands too. The more land it creates, the farther its maritime boundaries can extend.
The logic sounds reasonable. But it is not that simple. At least two countries have demonstrated this in different ways. One ended up losing in an international court, while the other remains a source of tension to this day. Before getting into their stories, it helps to understand the basic rules first.
The Basic Rules: Reclamation Is Allowed, But...
Under international maritime law, or UNCLOS, a country’s maritime zones, from its territorial sea to its Exclusive Economic Zone (EEZ) extending up to 200 nautical miles, are measured from its coastline.
If a country reclaims the sea and the new land is directly connected to the existing coast, the baseline used for measurement can move slightly outward. This is where the assumption that reclamation automatically expands maritime claims comes from.
The problem is that two catches make this assumption wrong in most cases. The first is when the new land stands alone in the sea, separated from the existing coast. If it is an artificial island built from scratch, international law does not consider it an “island.”
Such artificial islands are entitled only to a small safety zone, up to 500 meters from their edges. They do not get a 12-nautical-mile territorial sea, let alone a 200-nautical-mile EEZ.
The second catch concerns the original status of a reef or feature at sea. Whether it is a true island, merely a bare rock, or completely submerged at high tide is determined before humans alter it.
No amount of reclamation or construction can change its legal status. These two countries provide some of the clearest examples of both catches.
China: Turning Reefs into Bases, But Still Losing in Court
Between 2014 and 2015, China reclaimed several reefs in the Spratly Islands in the South China Sea and turned them into runways and full-scale military bases, including Mischief Reef and Subi Reef. The problem was that both reefs naturally submerged completely at high tide.
The Philippines brought the case to arbitration. On July 12, 2016, the Permanent Court of Arbitration ruled on precisely the second catch above.
Because the features were originally “low-tide elevations,” turning them into artificial islands did not change their legal status. They remained ineligible for a territorial sea or EEZ and were entitled only to a 500-meter safety zone.
The tribunal also concluded that China’s activities there violated the Philippines’ rights within its own EEZ. China rejected the ruling and has continued to strengthen its bases there. But under international law, the EEZ claims generated from those artificial islands have never been recognized as legally valid.
Japan: Two Bed-Sized Rocks, a Sea Claim as Large as Germany
While China’s case has already been decided by a tribunal, Japan’s case over Okinotorishima remains unresolved. At the southernmost point of its territory, only two rocks remain above water at high tide. Each is less than 10 square meters in area.
Since 1987, Japan has reinforced the two rocks with concrete to keep them from sinking. It has since treated them as full-fledged islands and claimed an EEZ of around 470,000 square kilometers around them, roughly the size of Germany.
China and South Korea reject the claim. They argue that the features are merely rocks that cannot sustain human habitation or their own economic life.
As a result, they say, they are not entitled to an EEZ at all. Because the dispute has never been brought before an international court, it remains a matter of competing unilateral claims.
The dispute briefly escalated into a real incident on July 19, 2026, when a Chinese destroyer conducted live-fire exercises in an area Japan claims as part of its EEZ. Japan strongly protested. China reiterated that it does not recognize the EEZ claim at all.
No formal violation has been established because there is no binding ruling between the two countries on Okinotorishima’s status. That is precisely what makes the issue vulnerable to repeated friction.
So, How Far Can a Country’s EEZ Really Expand?
The answer is not about hectares or kilometers. It comes down to three things.
First, whether the new land is connected to the existing coast or stands alone in the sea. Second, the original status of the feature before humans altered it. Third, whether the maritime boundary has already been settled through an agreement with neighboring countries.
A 2001 ruling by the International Court of Justice in the Qatar-Bahrain dispute added another limitation. If a feature appears only at low tide and lies in an area where the maritime claims of two countries overlap, it cannot be used as a reference point for determining the boundary.
So far, no country has successfully expanded its EEZ through reclamation without facing objections from another party. There are attempts that have lost in court, such as China’s case, and claims that remain unresolved and vulnerable to friction, such as Japan’s.
A country’s footprint on the map may grow through sand and concrete. But the extent of its maritime claims is still determined by international law and its neighbors’ willingness to agree, not by how far the reclaimed land is pushed into the sea.
