I doubt the Chinese conspiracy

There's a lot of people who, both for good or for bad (Guild Wars2 Gold), do a lot of playing around with common network equipment to try to mess it up. They're either trying to find out how hard it can be pushed, look for problems, or look for ways to exploit it, either to do the exploiting themselves or to beat the malware writers to the punch. That's on top of US engineers using Chinese sourced chips to design new products, who also dig fairly deep into the chip design.

So it would be tough to hide such a massive conspiracy.

Now on the other hand, there's more credible concerns that they may try to do it on a limited basis with specific components that go to the military. Although on high end equipment, the military tends to be really specific about sourcing requirements, the closer you get to an off-the-shelf product (Guild Wars2 Gold), the greater the cost-premium of doing so.

It's just as likely the counterfeit parts story is due to corruption at Chinese suppliers as it due to conspiracy, but if they wanted to enact such a conspiracy, corruption would be a good cover story.

There's also suggestions that the US has been putting out defective industrial equipment, etc in markets where they know they'll find their way to Iran, and hopefully into their nuclear program in place of the functional equipment they're actually trying to buy.