Assuming, for the sake of the question, that a well-resourced adversary (another country, most likely) had the means and motive to conduct economic warfare against the United States through large-scale counterfeiting, what would be the scope of the impact?
For example, if shipping containers full of $100 notes that were indistinguishable from genuine US currency were distributed around the world, would that be enough to destabilize the US dollar domestically, or would it be just a drop in the bucket relative to the amount of dollars available globally?