Unfortunately, the espionage screen suggests that the game includes some form of cassus belli or similar justifiable denunciation mechanic. No such thing exists. The AI views your denunciations or DOWs and the spying events that bring up these options to be two completely unrelated phenomena. Being that this is the case, I wish the programmers didn't include the option to denounce or DOW after catching a spy. After all, you can always denounce or DOW them after receiving the notification without the meaningless prompt. Why suggest that there is some relationship between denouncing and spying with a prompt?