...you do realize that during the last civil war the fanciest equipment was artillery, and both sides had access to that? Oh, and ironclad warships. Like, two of them.
Where exactly are you planning to get advanced missiles with satellite-aiming capability? Or /tanks/? Civil war is not a practical possibility unless one part of the existing military winds up fighting another part. Very few people in the modern world, let alone those with the necessary advanced military training, have the sectional loyalties to be dragged into something like that the way Lee was. We are living post-WWII. Very few people are Virginian /before/ they're American.
Mind you, most historical civil wars before the last couple of centuries were larger-scale coups with pieces of the official military fighting one another. See, Rome. Our command structure is set up to minimize the possibility of this, but that doesn't mean it couldn't happen someday, somehow. After severe sociopolitical stress points that don't currently exist developed.
The fact that we no longer have even the possibility of a well-organized militia capable of resisting government oppressions, should the government become seriously oppressive, I actually do acknowledge is not a good thing, and would not have been seen as such by many of our Constitution-framing forebears who had just got done being rebels themselves. But modern military tech in civilian hands is a worse thing, and I don't think being in denial about the potential of a bunch of revolutionaries in a country like this one to do more than get wherever they make their move comprehensively destroyed is a good idea.
Unless, you know, you want to live in Afghanistan. Brave people versus invading USSR! They're finally gone, shit, our country is completely wrecked. People versus other people in the wreckage! Oh, fuck, some even crazier assholes brought in some cash and techniques, which was good, but got the world's most powerful army mad at us. Panicking people who have been fighting our whole lives versus yet another invasion! Gaaaaaaaaah! Who needs a central government that isn't run by my faction? Pickup trucks can drive over thirty miles per hour on some of these roads! Abdur Rahman Khan built this on in the nineteenth century!