I'm not trying to come up with a general legal definition of "international incident." I am merely disagreeing with calling this specific thing an "international incident," at least unless the person using the term explains why they chose that term, and why that term matters in this case. But for me, international incident has much more weight then a fence that was built in the neutral area between two sovereign but friendly open-border nations.

If you still want to go down the international incident branch, I'd consider the agricultural practices of US farmers in California drawing too much water for our downstream neighbors much more appropriate.