I don't see why it matters where the bitcoin was mined. Most blocks are won by massive mining operations, or mining pools. It's an activity that truly knows no boundaries. Technically, the government could setup a huge mining operation of its own to win blocks, but that would be an enormous expense, and wouldn't guarantee winning the blocks. Anyone can discover the right hash. I still just don't see why the geographic location of the mining operations is important, or would justify the expense to the American taxpayers to build and maintain the necessarily large mining farm.