Recall the story of how the NSA was intercepting the shipment of US-made routers and secretly installing backdoors in them that would enable the NSA to gain access to their entire traffic and users before re-sealing the packages and forwarding them to the unwitting recipients.
It turns out that there are internal NSA documents containing actual photographs of this being done. These documents and photographs are contained in Glenn Greenwald’s recently released book No Place to Hide.
Recall also how the US government vociferously accused Chinese manufacturers of routers of doing exactly this same thing in the service of the Chinese government, even though they never produced any actual evidence that this was the case. This resulted in one Chinese manufacturer withdrawing his product from the American market because he did not want to deal with the headache of defending himself from these accusations.
I suspect that publicly accusing the Chinese of doing what they themselves were doing was not just part of a propaganda war but was designed to make companies that use routers wary of Chinese manufacturers. Those companies were then more likely to purchase routers made by US manufacturers and thus were walking straight into the NSA’s trap.