I agree that the US is not much interested in bridges. Also although Tor project developers very frequently meet up with law enforcement and such, they are to the best of my ability to tell not in cooperation with law enforcement at all. Mostly they just tell them the basics of how Tor works, shit that all of us already know. Also Tor project very frequently gives the same information to a wide range of people, if I recall correctly they helped Wikileaks with their hidden service configuration as well. So they are pretty impartial about who they will talk about Tor with, but they are quite dedicated to Tor itself and keeping it as anonymous as they can for all who use it, and I do not think for one second that they will compromise Tor for anyone unless they are absolutely forced to (and even still there isn't much they can do , although they could be forced to give up bridge IP addresses perhaps. EFF lawyers back them up for free, so they have access to a pretty powerful group of lawyers to help defend them from legal attacks). I would also like to point out that although from an active internal perspective, the distribution of Tor nodes makes it unlikely for such an attacker to correlate traffic, but from a passive external point of view it is quite likely that the US government can correlate large amounts of Tor traffic. NSA has access to multiple Narus Insight super computers with direct access to major IX's in the USA, so it is very likely that they can externally monitor a lot of Tor traffic passing through nodes they don't own. Thankfully NSA is prohibited by law from using this intelligence against Americans who are not in contact with terrorist or foreign intelligence agencies, and I think they are actually restricted to only targeting terrorists and foreign intelligence agencies in the first place. Of course they do whatever the fuck they want, but they don't want to fuck with us. Mostly, although it can also be a problem for people trying to find bridge users to do other attacks, particularly known rough geolocation + Tor client enumeration & geolocation to narrow in on shippers. Even more concerning is who runs these bridge pools? What stops an attacker from purporting to run such a pool, but only providing compromised nodes that they control? At least when we use the official Tor bridge pools, we know that anyone is free to publish a legitimate bridge, and that there is a chance we will get their legitimate bridge when we request bridge addresses. The biggest problem with exit guards is that they do massive damage to Tor's ability to prevent traffic linkability. The Tor devs will never implement exit guards, historically preventing exit traffic linkability has been their primary focus.