I see you know nothing about bitcoin. Let me explain: BTC is based on the blockchain, a decentralized system. Even if the US (or whatever country you can imagine) took the control of all the internet, it will be impossible to control Bitcoin, for many of the "parts" of it are stored offline. Furthermore, this is impossible for one country to take the control of all the internet, isn't it?
So, this is impossible for one country to take control of BTC. If you were talking about the legal activities, in what sense it is even possible for one country to take control of it? Us is not the center of the world, my friend. Even when it is a powerful nation, there are not powerful enough to take control of something ruled bu the wide people. This is just impossible.
So relax.