There are but now that "voicing opposition of the government" makes you officially a terrorist in the US now not to mention that being the de-facto policy in the whole west, get ready to learn russian or chinese if you want to get into any of the publicly accessible ones. Then, of course, you will have to deal with their bullcrap so it'll be a rock and a hard place situation.
My advice is to not use public forums if you intend to keep your identity hidden from glowneighbours. You're going to need to find these groups who have gone completely underground and try to get an invite because that will truly be the last bastion of anonymity on the internet going forward. Even that won't last forever.