I do not think any country could invade the US. Every house you go to they have atleast a gun in the house. In the South its different. Theres bout 5 guns or more in each house. Does anyone agree with me?
I honestly think we could be considering the fact we really cant leave well enough alone and start helping everyone. And all it would take to beat us is china and russia and maybe korea.But we have plenty of allies mexico austrailie england. i would count cannada but you never here anything about cannada waging war so i doubt theyll do something. And there are plenty of nut jobs that know how to make crude bombs so tanks wont be a problem. Aircraft will be the only problem.
blah blah blah...let's get to the end of the world which'll happen right after USA gets invaded. I believe in the M.A.D. theory (Mutual Assured Destruction) which is both sides have enough nuclear capability to destroy both sides completely. Mutually assured destruction.
i would count cannada but you never here anything about cannada waging war so i doubt theyll do something.
If the war is sanctioned by UN/NATO, which it likely would be, then they'll have some involvement. They had combat troops in Afghanistan until recently.