Rynar wrote:
Water. Lots and lots of water.
Water helped, but it wasn't much of a barrier back when the U.S. was a fledgling country, especially against the world's most powerful navy.. or the second most, or third most. The U.S. Navy really did not become a major world force until just prior to the advent of the dreadnought battleship, and even then we were at best on par with Japan or Britain until the major ramp-up in WWII.
The main thing that stopped people from attacking the U.S. was that they were too busy fighting each other, for the most part, to concentrate everything they had against us. The exact reason depends on exactly when and which possible conqueror you mean; the British put us in fairly serious danger in 1812.
As we grew bigger, it wasn't water that deterred our enemies, at least not by itself. It was the prospect of having to conquer all that territory with an army you had to support
across all that water, when you also couldn't count on your own country and your colonies being left alone by everyone else. That didn't mean there weren't plans for more limited expeditions; after a dispute with Germany following the defeat of the Spanish fleet in Manila, there was a German plan to invade and take New York City and environs, with 3 battalions of infantry, and a battalion of engineers, and ransom it back to us for our compliance with whatever it was they wanted (which escapes me at the moment) and the fact was, it was quite doable for the German navy of the immediate pre-dreadnought era. The U.S. Navy at the time was more than a bit hidebound and obsolete;there was a ram ship (USS
Katahdin) in service as late as 1909.
Remember my analysis of what it would take China to conquer the U.S.? The real sticking point isn't getting together 6 million soldiers to conduct the occupation; it's having to supply those soldiers across the ocean. Conversely, if China just wanted to take Guam or Hawaii, that's a far more realistic number of soldiers to support, across less ocean, and could conceiveably be doable for China at some point.
This prospective tiny little artificial island country can really only count on not being worth attacking as a defense. But, if they aren't worth attacking, what do they have to sustain themselves? What industry will they perform?
I hope they don't count on fishing or drilling oil because most of that occurs near shores, and each country with a coastline already has an exclusive economic zone out to about 200 nautical miles they won't be welcome in - nor is any country terribly likely to listen to any protestations about inherent rights. They'd be relegated to the deeper, farther out part of the oceans where there are few fish and the prospect of drilling for oil is not as good what with the greater depth.