I am just pointing out that the opportunities are there and not necessarily the motives. My scenario is what I can come up within minutes of reading your initial post.

If it is in a cell phone tower per topic, you certainly won't find any pieces that can be serviced by the provider's own tech.

Network equipments sitting at the providers are the ones that are "banned". They are not for DIY supports. The vendor charge good money for a support contract for exactly this reason.

What if they were to collect the data silently and encrypted into internal normally unused non-volatile storage. After a few years when the storage is full or external trigger (say exception packets processed by the CPU matches certain CRC & payload signature), the equipment would "crash" and dump out the encrypted log file into the coredump.

The "helpful" support people at the China site would recommending the customer to ftp over their core dump. They would send them a "test load" a couple days later that magically "fixes" the system and to cover the track or "re-target" the system.

Re-routed?

"Law-full" access interfaces don't change routes. They just send a copy to whoever requests it.

..... it would not be a huge stretch to have our government wield some quiet and heavy power to inspect, dismantle or other tamper with, equipment on towers located on US soil.

As someone already mentioned, they could have bought land in the US and even paid almost Chinese wages to the poor people down there, if they really wanted to spy. There's no practical reason to build in Canada

Although I have no proof, I wouldn't put it past the Chinese manufacturers to put hooks for back doors right in the firmware/microcode of their chipsets.

But upon noting that a string of towers were to be erected along the US/Canada border, I started to think "WTF?"

Should I be concerned that my tinfoil hat is Chinese-made?

Whoa, thought this was the security forum for a second. This thread is just littered with empty reynolds wrap boxes.

NIMBY's

I've heard stories from employees of one of Huawei's competitors, and the topic of their espionage does occasionally come up.

Now, this is entirely hearsay but supposedly, for a while, wherever either Ericsson or Alcatel-Lucent would open offices, Huawei would too, within a few kilometers. This resulted in there being two Huawei branches in the same city, within a few km of each other. Furthermore, in their internal product feature roadmap, they started adding bogus features, because they noticed Huawei feature announcements to be rather interestingly timed. The bogus features started showing up too.

The more general allegation against Huawei is that it's backed by Chinese government money, with everything that brings with it.

I'd sooner believe that the US is trying to muddy the waters as to protect its own telecom equipment companies.