Sure, sure, they could. But that’s where strategy and planning comes in
We have one major advantage: they don’t even imagine we’re coming, that is they cannot fathom even the idea that seasteading can become a major factor in the future. For the experts, it’s not even on the radar, but I plan to put it there.
For the US, it would be an alarming development for a new nation to essentially sprout along its coast. Absolutely. It would be virtually intolerable. They would have to project force into there immediately, gain some kind of influence somehow. They’d undoubtedly send undercover infiltrators almost immediately. But we have nothing to hide, it’s all up and up. I plan to actually convert such people simply by them viewing and living in that region.
But let me tell you my real plan and why I think they will not only allow it but embrace it, and why this subversive idea may end up one they’d welcome, to their own ultimate long-term detriment.
For one thing, it will be started by people with American citizenship, meaning they won’t perceive it immediately as a threat. Probably for the first many years this will be the case. And even though I will declare the intention to forge a new nation up-front, they won’t take it seriously. But they’ll help spread the news via media and the like.
Secondly, we may be able to replace the entire world’s fuel importation problem with something like mass-grown kelp farming on the open ocean. If this plans proves viable, they will certainly embrace it. They’d be trading a much greater problem, energy independence away from the middle-east, for the much smaller concern of seasteading on their shores.
That should buy us enough time to attract many more people to live there, to build infrastructure, and altogether achieve critical mass.
I’m under no illusion that they could crush this plan like a bug if they so wanted. What’s needed, ultimately, is luck
And I plan to roll the dice.
The same was true of the US back when it was a fledgling republic, and it was really Napolean who kept European attention off the US. I will need a similar stroke of luck for this plan to be pulled off.
But if it all comes together, then by god, we will have a libertarian republic at last and all bets are off. Everything changes.
And what I’m banking on is that the financial lunacy of the US federal government will ultimately keep their attention off me. Another financial crash would be delivious for a libertarian society built on a crypto-currency. Have you heard about the recent bitcoin price rise? Apparently people in europe, with their failing economies, are flocking from the Euro into bitcoin. Let’s pretend we bitcoin supporters didn’t predict that 
Secondly there’s the absolute idiocy of the socialization of health-care. As if people didn’t already have a reason to foot-vote because of massive land and housing costs and taxation. There are likely many doctors that would love to move off-shore and restore the original market-based doctor/patient relationship. Especially the high-end doctors that would otherwise see their wages cut by the gov.
And if things really do get too hot, there’s always the ability to simply float away from the coast and roam the Pacific as desired. How many ideas and notions and good things have been spread worldwide by persecution which drove its adherents out of a central spot. It was just as true of Christianity in the ancient world as it was true of jazz in the modern, which was driven out of New Orleans by the Navy.