https://en.wikipedia.org/wiki/Football_War

https://en.wikipedia.org/wiki/Paquisha_War

https://en.wikipedia.org/wiki/Cenepa_War

https://en.wikipedia.org/wiki/Beagle_conflict

And that's not counting the Falklands war because Britain doesn't feel like it belong in the neighborhood but it's still an invasion of sovereign territory out of nationalistic motives

I'll grant none of those was a major conflict and that it's an interesting case but still. Maybe the fact that apart from Brazil, they have a language in common makes it harder to sell the neighbour as a foreigner ? What else could it be ? I am genuinely curious