You bring up a very good point and it's worth reiterating that the Kremlin reverted to use paper instead of computers to discuss sensitive topics. [1]

I wouldn't be surprised if any network connected device is vulnerable to being exploited, even if not directly connected to the internet, by association of other devices on the network.

[1] https://www.usatoday.com/story/news/world/2013/07/11/russia-...