A Primer on Boundary Disputes

December 1, 2019
Marissa Wood

International boundary disputes, both on land and at sea, have been a particular focus of mine for the past few months. At the end of the year, we are unveiling our “Disputed or Contentious Sovereignty” collection of annotated points in the Sovereign Limits web research portal, and in October, I presented on boundary disputes for the 2019 NACIS (North American Cartographic Information Society for non-map nerds) conference in Tacoma, Washington. This blog provides an initial overview on how we at International Mapping monitor and maintain boundary disputes. 

Map of the world showing hundreds of small red dots marking areas of disputed or contentious sovereignty.
Sovereign Limits “Disputed or Contentious Sovereignty” point layer.


Boundary disputes come in many forms and are therefore somewhat complicated to count and catalog. From the outset, Sovereign Limits has kept track of disputes where two states have clearly defined opposing claim lines on land or over sovereignty of islands. But these account for only 74% of all of the disputes we maintain records on. The rest fall under our category of “contentious” sovereignty. This intentionally vague label has allowed us to broaden our definition of disputes to monitor less clear-cut but still important conflicted areas.

Areas of contentious sovereignty include, for example, the dispute between Afghanistan and Pakistan, where Afghanistan disputes the British colonially imposed boundary, known as the Durand Line, but it does not offer an alternative claim of its own. Rather, Afghanistan would like to renegotiate the entire frontier with Pakistan, since both states are now on more equal political footing than they were in 1893 when the Durand Line was initially delimited (Pakistan, then part of British India, had the backing of all of the United Kingdom’s technical prowess, military strength, and knowledge of how to create frontiers with the express purpose of undermining the localities they were occupying; meanwhile Afghanistan struggled at the negotiating table and fought to maintain its independence at the cost of territory and a manageable boundary).

Afghanistan in 1893. Map from the Library of Congress.

Contentious sovereignty also includes maritime disputes over features that can or cannot be utilized to generate an exclusive economic zone (EEZ). Some notable examples in this category include Spain’s dispute over Portugal’s use of the Savage Islands to generate an EEZ, or China, South Korea, and Taiwan all disputing Japan’s use of Okinotorishima Atoll in the same manner. 

Cool Stats

With those definitions in mind, we maintain a database of disputed and contentious sovereignty for Sovereign Limits that includes about 200 individual locations. The state with the most of these is China with about 30 places of disputed or contentious sovereignty, ranging from high profile territorial conflicts with India to lesser known areas of contention with North Korea.

The largest dispute, where the most territory is at stake by area, excluding maritime space, is between Morocco and Western Sahara. The second largest land dispute is between Somalia and Somaliland. It is interesting that the top two in this category are similar separatist territories claiming their own independence from the state to which they have historically been a part of.

Showing Western Sahara as disputed territory, and Moroccos line of control almost all the way to the southern border with Mauritania.
Map showing the disputed boundary(ies) of Western Sahara. Morocco maintains control of territory up to the dotted line, which is actually made up of sand berms visible in satellite imagery.

Once you include maritime space, where competing states can claim 200 nautical mile EEZs from their coastlines, the picture shifts. The dispute between Argentina and the United Kingdom over South Georgia and South Sandwich Islands generates the greatest potential maritime space at over 1,431,000 square kilometers. It’s followed by the United Kingdom’s dispute with Mauritius over the Chagos Archipelago in the Indian Ocean. Western Sahara still comes in third when maritime space is taken into account for total area disputed.

The smallest dispute by area is between Croatia and Slovenia over a tiny plot of land referred to as Area 9.4 by Croatia and part of the Prezid series of disputes. It has an area of only 1.7 acres (just a little bit bigger than my suburban yard…). Interestingly, the seven smallest disputes in Sovereign Limits are all between Croatia and Slovenia and are still contested despite a 2017 Award issued by the Permanent Court of Arbitration (Croatia unilaterally withdrew in 2016 and does not recognize the Award). In addition to these seven smallest, there are five more disputed areas between Croatia and Slovenia, for a total of eleven, including one over the location of the maritime boundary in Piran or Savudrijska Bay. Furthermore, Croatia has disputes with all of its neighbors except Hungary. For more information on why this is, check out my blog on the Balkans.

Top: large scale map of the 1.7 acre Prezid dispute
Bottom: Balkans regional map featuring Croatia's disputes
Croatia and Slovenia disputes featuring tiny Prezid.

I could spend the rest of my life writing about boundary disputes and never explore them all. Sometimes disputes are resolved, and there are always more to add. I’ve written about a few of so far for the Sovereign Limits blog (the post on Egypt and Sudan has it all with terra nullius, bad colonial boundaries, and high stakes maritime space) and will continue adding to the list. If this is something that interests you, please check out my NACIS talk, where I go into some additional details about some of the most interesting (to me) international boundary disputes.

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