More likely no personnel was required because they simply paid off American manufacturers to implant these circuit boards in computers they knew were going to be shipped and used overseas.
The bottom line, though? This isn't surprising. Nations spy on each other. A lot of nations have been engaging in a lot of phony outrage over our NSA spying who are doing the exact same thing, but have managed to keep it secret. Any nation who is using imported computers in sensitive operations should know enough to check those computers for possible spy hardware.
I would be surprised if they didn't simply have them installed in all machines and only have them activated in 100,000 devices overseas. Logistically seems simpler to coordinate if component-cost is a non-issue for the agency.
If they have access to the manufacturers, it would be the simplest, minimum-effort, minimum-risk approach. It is also what I would do, given the chance.
Taking into account what we have learned this year about the extent of the activities of the intelligence services, I think we have to assume that somebody (Whether the NSA, the FSB or somebody else) has compromised the manufacture of at least part of the electronics and/or software supply-chain.
I am not too sure what it would take to audit the software and hardware components in common use today?
There is no evidence (yet, anyway) that any other country does surveillance at the level the US does. Stealing emails here and there is a completely different thing from spying on potentially every person in the world, no matter how you try to spin it, in the same way that murder and genocide are different things even if they are both about killing people.
But at least these leaks made the US halt their phony outrage at "Chinese hackers", which is a positive thing. We can move on to have a real grown-up debate about the effects of surveillance on democracy.
The bottom line, though? This isn't surprising. Nations spy on each other. A lot of nations have been engaging in a lot of phony outrage over our NSA spying who are doing the exact same thing, but have managed to keep it secret. Any nation who is using imported computers in sensitive operations should know enough to check those computers for possible spy hardware.