This is a fictional stance on how USA, US govt agencies could take down Bitcoin when the next financial crisis happens. The next financial crisis is looming around the corner, could be tomorrow, could be in 2017, or 2018.
They have tested that they can seize a website, dot.com or not easily via their regulatory framework, legal or otherwise sanctioned as legal. (remember lauching missiles that are not legal in UN rules yet they did it and nobody said nor did anything?!)
They can block the blockchain. Pun intended. By systematic restriction to access of the IP protocol and TCP over IP protocols such as the ports that connect to Bitcoin nodes. In THailand and in Malaysia, for example, some news sites you are not able to connect to. Medium is not available in Malaysia.
Take out the mining pools. Block them. Restrict their IP address, seize the website access. No mining pools or a disrupted mining pool means a standstill in Bitcoin network. No transactions, mempool will skyrocket, in fact the mempool might not even exists since no transmission of data is propagating.
And it won't be difficult to send a drone to Iceland to wipe out Genesis Mining, or a few more physical attacks at mining pool facilities that are in isolated locations.