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...doesn't "attack" american companies with covert implants.Specific example aside, it's worth talking about why this does happen. "Black bag jobs" can mean "we didn't get a warrant", but they can also mean "we got a warrant and still aren't telling".
Even given a court order, there's still a possibility that employing surveillance by fiat will cause somebody to leak, or modify how they handle data, or simply reveal information about what sort of surveillance tools a given agency employs. Given that a FISA order can be obtained without a defendant, getting a court order and then doing the thing secretly anyway gives a sort of "bowling with bumpers" advantage where the project is approved if it gets revealed, but also done without revealing anything if it isn't.
More disturbingly, there's also substantial evidence that the NSA attacks companies covertly in places where they couldn't get a court order. Taking a specific device out of the supply chain and adding surveillance before it's shipped to the destination is a warrant-worthy project. Setting up systematic physical vulnerabilities with a use case of "turn it on some time in the future to get something interesting" isn't in the purview of a FISA order, so if the NSA did do that it would have to be without an order.