Yeshayahu 45:7 I form light and create dark, I make peace and create evil - I, Hashem, do all this.
In bringing down Babylon to uplift His people, G-d reveals Himself as the Creator of all - both the "light and the peace," the good, for His people and the "dark and the evil" for Babylon.  This is stressed here for the conquering Persians to hear, because they believed in a dualism of gods, one of good an done of evil.  But G-d is above all limitations and He can do these contradictory things.  And even the evil He brings about is for purpose of bringing good, because the dark is a prerequisite to light.  Even the wars that He brings about are for the purpose of bringing world peace.

MeAm Loez - Yeshayahu