The land on the borderline would technically belong to both neighboring countries as each one's territory ends there. So in the case of one country deciding to build a wall, would that country build the wall just inside their border to not require consent from the other country?

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    I don't think so. Countries don't put border walls exactly on the demarcation line. As far as I know, border walls are usually built at a distance to the exact border line, so a simple answer might be NO, you don't need your neighbors consent to build something inside your territory. Feb 1 at 23:36
  • "Despite the rapid increases in wall construction and the violence surrounding them, border walls remain under-researched in international legal scholarship." (Moria Paz, 2017)
    – Stuart F
    Feb 2 at 10:48
  • The borderline is a one-dimensional line on the earth's that has a surface area of zero. Or it is a vertical two-dimensional surface, the extension of that line, dividing airspace and subsurface water, soil and rock, that has a volume of zero. Regardless of how you look at it, there is no part of the border that belongs to both countries unless there is a condominium. The typical approach, therefore, is to build the wall a little way away from the border so as to avoid mistakenly encroaching on the neighbor's territory.
    – phoog
    Feb 2 at 13:50

2 Answers 2



Each side is free to build walls on their side of the border. See, for example, the border between the two German states during the Cold War. Since such a wall must not encroach on the foreign territory, it cannot be literally on the border -- there will be a strip of territory between the wall and the border. There are even cases where both sides build walls on their side, e.g. the Korean DMZ.

Countries might voluntarily enter treaties which effectively prohibit such a wall. Or regulate where there must be gates, and who can cross. But that is a special case, not the general one.


The country wishing to build a wall would do it inside its borders. Using even a small part of the neighbor's territory would be sure to lead to serious political issues. This is unless the neighbor agrees, which would be unlikely, as in most cases only one side sees an interest in building a wall.

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