I think organized crime doing this sort of thing is at least plausible, but I agree that state-funded seems likely. For criminal motive: I've read claims that

I think organized crime doing this sort of thing is at least plausible, but I agree that state-funded seems likely. For criminal motive: I've read claims that some cartels have infiltrated telecom companies before, to track down informants or keep tabs on investigations. But from this angle, attacking cellular networks makes more sense than undersea cables.