I don't think there's necessarily an assumption that it was Russia or China this time (the Chinese-sounding name is almost a dead giveaway that it's someone oth

I don't think there's necessarily an assumption that it was Russia or China this time (the Chinese-sounding name is almost a dead giveaway that it's someone other than China), but the security world does believe quite strongly that it has been Russia (SolarWinds) and China (Juniper) before, so they are the usual examples.