Comment by ETH_start

Preventing people from encroaching on your nation is fundamentally no different than preventing people from trespassing on your property. It's not anti-liberty, since we don't have an inherent right to any land on earth. That right to occupy a piece of land, to the extent that it exists, emerges through homesteading and the principle of First Possession.

As for U.S. territory, yes, you can make a case that it's the collective property of American citizens who then decide how the property will be governed through their elected representatives. How is that anti-liberty?