Hi,
I was just reading a paper on traffic confirmation attacks over here https://arxiv.org/pdf/1808.07285v1.pdf. This attack runs with the help of deep learning algorithm called DeepCorr. This attack can be run in a Five Eyes country or an authoritarian regime like Russia where companies are compelled to cooperate with the government making this attack plausible. The ISP and the website operators are the two endpoints for this attack. This attack was able to achieve a success rate of over 96% which represents a serious threat to Tor users in these regions. The paper also includes some countermeasures on how to defeat this method of traffic confirmation.
Thanks.