Interestingly, fiber signals can be split passively[1] (without a transducer), which should be extremely reliable. No idea what technology this kind of application would use though.

[1] https://en.wikipedia.org/wiki/Fiber-optic_splitter

We don't know the architecture of this hypothetical spy splitter tho in the current case. It can be less covert and more of a complicated config, etc.

How often does the entire west coast of the U.S. lose Internet connectivity to the entire continent of Asia? That gives you a constraint on how often that type of failure actually occurs.