R’ Elazar said: One who becomes compassionate to the cruel will ultimately become cruel to the compassionate, as it is written, “And Saul and the nation spared Agag and the best sheep and cattle.” [I Samuel 15:9], and it is written (Ibid. 22:19) “And Nov, the city of priests, he smote with the edge of a sword.”
Tanhuma, Parashat Mezora,1; Yalkut Shimoni, I Samuel, Chapter 121.
I'll leave it up to you to work out the contemporary political relevance.
Apologies for my bad loshn koydesh in entitling this post originally. Thanks to Jogo for pointing out my error, in an e-mail appropriately labelled shmendrik.