I might be biased ive had many generations of my family in the military. I doubt the next 2 most powerful countries maybe 3 could defeat america on its home terrian. Thats around 1.3 million active well trained soldiers plus the last gen soldiers [ vietnam men who mastered the art of geurilla warfare] in their 40s-50s and then countless civilians who would fight. [and trust me some of our ghettos have some really nasty mofo's
] But if you did defeat our main military force you wouldnt have a home to come back too because it would be nuked.