An FBI PowerPoint deck on the threat of getting counterfeit routers and such was reportedly found via an Internet search and posted here. The FBI (allegedly) makes the case that buying counterfeit network gear and getting your network gear with a trojan installed by a foreign power are linked.

Counterfeit gear has nothing really to do with having a backdoor installed. Having counterfeit gear can increase the likelihood of having some kind of rootkit or malware, but only in a general sense. If a foreign power wants to get you, it will do so on what looks like genuine gear in the original packaging - it doesn't need knock-off gear to do that (see the public domain examples listed in the article).

Creating a homeland security nexus is a good path to funding, albeit not always a legitimate case. There are too many examples of this bad behavior to list. The deck contains a point about vendors needing to link government sales and brand protection - instead, the point should be that government sales need to link to a trusted supply path.

Getting a trojan in new network gear is a big concern for very few people, and those few people may want to consider buying direct, rather than through resellers/channels.