Countries should assume that other countries are spying on them, military enemy or not. This is how the world has worked for the past 70 years, and it's not going to change.
Spying yes, comitting sabotage and other things that get called "acts of war"... No.
Imagine this hypothetical scenario. Germany want to put a backdoor into the US phone system. During 9/11, this attempt causes a breakdown and the phone system to crash an hour after the plane hits the tower. News papers goes out with "sabotage of the phone system, Germany suspected of participating in terrorism!".
Would you just shrug and say that "Countries should assume that other countries are spying on them"? People who lost family members to the chaos of no telephone service should just accept it as normal behavior, nothing to complain about?
> I have no problem with the NSA spying on foreign communications or disrupting them.
Should the rest of countries just assume that the US is a permanent military enemy? You don't seem to have a problem with treating them as such.