[Alteveer]

Can spies be killed in a non-spy attack (e.g. cruise missle, aircraft attack)?

[thedestro]

No sir

[Count Rupert]

Actually defeat alerts will kill up to 5 spies.

Quote

If an attacker is unable to battle a defending nation because the defending soldier numbers are too low the defender will automatically be placed into Anarchy, up to 5 defending spies may be killed, 5% or up to 10 technology levels, 20% or up to 40 infrastructure levels, and 5% or up to $5 million in money may be destroyed (not stolen).

[thedestro]

I wouldn't classify that ^ in the same category, but yeah.