Ken:

There has been no fundamental change to the nature of transportation in the last 30 years, or for that matter for the last 70 or more. It is still ships, planes, railroads, cars and trucks. We were global 30 years ago and truly global, probably the most global ever, between 1942 and 1945. What has changed about the nature of transportation that makes containment not viable?

Communications has been affected by the internet and sat com but it is just a matter of degree. You could talk around the world by radio decades and decades ago. If you are worried about cyber sabotage, set up defenses. Men have come up with defenses for every threat, this is just another. I don't see how that makes containment not viable. You can't push a submarine or a container ship through a fiber optic cable.

Lack of resources makes a perimeter impracticable, not undesirable. But we don't man most of the perimeter. Countries that aren't enemies do. And to effectively man it, all the have to do is stay not enemies. That seems a less expensive way to do it.