Is the US running an empire?

[carl]

Ease of transnational movement, porosity of borders, lack of an 'Iron Curtain,' etc.

That applies to individuals and has mostly to do with political controls or lack thereof at borders. It didn't have anything to do with a hostile nation state having free access to the oceans so its' navy could roam around easily. That is what I mean. That is what the perimeter looks like it is about.

No but you can get your message of revolt or whatever to a worldwide audience in seconds -- if you're flexible enough to do that; most large nation are too bureaucratic to be effective at that, 'movements' of all sorts tend to be quite good at it -- and thus at attracting adherents or supporters everywhere.

That has nothing at all to do with what I'm talking about.

A perimeter is undesirable because once established, it has to be maintained in some fashion. Maintenance entails costs of some sort and everything has a cost. Better to let it just fall into disuse.

Well naturally a perimeter has to be maintained. But it is established because there is some benefit to be derived from it. If it falls into disuse you lose the benefit.

Countries who are not enemies (and those who are enemies) shift and change. All countries cater to their perceived interest; they will support our 'perimeter" as long as it suits. As the the Persians, the Greeks, the Romans, the Byzantines and the British discovered, 'friends' change...

That is a given and you adjust as things change. The ultimate goal remains the same.

A far better solution than a perimeter is the ability to respond to provocations with the proper instruments, political or military, rapidly and overwhelmingly locally to deter future provocations and that's, thankfully, where we at last seem to be headed. Long past time...

I disagree. It looks to me as if we are still pursuing the same strategy. We are doing our best to make sure that potentially hostile countries that may be able to deploy powerful navies can't easily get to the oceans.