1. More evidence suggests that NSA does not know how to decrypt state-of-the-art ciphers than suggests they do. If they did know, it's far less likely we'd have nation states trying to force Apple and others to provide backdoors for decryption of suspects' personal devices. (Also, as a general rule, I don't put too much stock in the notion that governments are far more competent than the private sector. They're made of people, they pay less than the private sector, and in general, if a government can barely sneeze without falling over, it's unlikely they can beat our best cryptologists at their own game.)

2. The operative assumption in my statement is that the government does not possess the key. If they do possess it, all bets are off.

3. This thread is about a hypothetical situation in which the Korean government did store backups with a U.S.-based cloud provider, and whether encryption of such backups would provide adequate protection against unwanted intrusion into the data held within.