Given premises: a) state with a hand in supplying gear will have a natural "home advantage" spying AND b)"everyone spies / does sigint" and c) it is basically impossible to detect a well-engineered backdoor then:

1) I believe we don't have to be cynical about the U.S. pushing say, Cisco, it makes perfect sense; I don't think that agenda is actually hidden. 2) It makes perfect sense to choose gear for critical infra based on which supplier states you believe will do you the least harm.