alt Hacker NewsAmerican security, and indeed the entire pax Americana has been predicated upon your country's network of global military bases and your carrier battle groups. This is what enables the USA to decisively influence any conflict anywhere on the globe.
Those bases would need to disappear in order for your comment to be true, and despite two thirds of your electorate who didn't vote against the future dementia ward patient currently in office, I don't think Americans are ready to accept a world where American foreign policy cannot be promulgated more or less at will, which is what isolationism would entail.
No, America's influence over its globe-spanning empire is predicated on that. That's not the same thing as it's national security. It would do just fine if it weren't the head of a global hegemony, although it might have to start living within its means.
Security-wise, two oceans, vassal neighbours and two thousand nuclear missiles have it covered.