Before addressing ways America might blunt the force of a karmic blowback, the nationhood must acknowledge its habituation to inhumane, imperial actions that could rightly result in the accumulation of negative karma. Cornell West, in his book, Democracy Matters (published before the "black lives matter" slogan), discusses "matters" as "things relating to" -- and classifies the unwillingness of some citizens to own up to America's actions as symptomatic of a cowardly, immature adolescent:
". . . even as we grow old, grow big, and grow powerful, we have yet to grow up,"
The United States continues to do the same imperialistic things it did over a century ago--even worse; growing more blatant in its upfront lies. Each new public episode fortifies the administration's arrogance. It can openly fabricate reasons to war, even murder its own people in broad daylight without reprisals. That's how bad it's gotten. We're in big karmic, cancerous trouble.
An inside job killed the Kennedys. A "9-11 gate" is a patriot's pipe dream.
Optimism for the nation as a whole is still a valid position, but the advice, "Be ye separate" might turn out to be the best advice for individuals, a personal, singular safety net. Hope to God it holds.