The fact is nukes and tanks and jets are technology that already exist, today. They don’t just go *poof* and disappear once you and your neighbors decide to band together in a non coercive lifestyle. If Russia (or China, or the Middle East, etc.) exist on the other side of the planet, they will come and take you over. If you say “but why would they do this?” Then look at history. Human history is filled with countless examples of people colonizing far off places, often times not even at the behest of the state, but for their own self interest (glory, money, etc). This will not stop.

If you somehow imagine those states as also disappearing during your ancap revolution, than it will become an arms race to see who can build a state and capture the most territory and resources first. Why? Because they are incentivized to do so, and incentives matter.