According to one report 74% of bitcoin mining is linked to China. <a href="https://bitcoinmagazine.com/articles/report-links-74-bitcoin-mining-china-sees-threat-network/" rel="nofollow">https://bitcoinmagazine.com/articles/report-links-74-bitcoin...</a><p>If that's true. Chinese government can do 51% attack at any time. They just contact different miners either operating in China or having family there and tell them what to do.