None of the above, it's not really like the Chinese or Russians are any smarter than Americans. No one is going to invent some magical eavesdrop machine that op

None of the above, it's not really like the Chinese or Russians are any smarter than Americans. No one is going to invent some magical eavesdrop machine that operates on some principle that hasn't at least been thought about by the other side. If the Americans did learn about some new machine the other side invented from an insider, it would be trivial to drop the knowledge on the desk of the most relevant researcher, tell them to publish a public paper on it, and then use that as justification as to why new countermeasures need to be added to the embassy SCIFs. You protect your insider by making it look like the tech is now common knowledge and protect embassy operations. All of the secret conversations and messages that occur in an embassy happen in a SCIF. If the other side can eavesdrop into those, you've got nowhere else to discuss these things so the only option is to build countermeasures. There are no juicy bits of intel floating around outside the SCIF that the other side couldn't gather themselves. If they can't eavesdrop into the SCIFs, then there's no immediate need to react. The other side isn't stupid, any false or misleading info you intentionally leak will eventually be figured out and then they'll know that you know they are listening (not good for your insider). The best course of action is to appear that you are acting independently of what the other side is actually doing, play dumb but don't be dumb.