Although the purpose of the destruction of Assyria was first to free Judah, it also served to demonstrate that the Lord reigns over all the leaders and all nations of the earth. Furthermore, both the Assyrian and Babylonian downfalls were partial fulfillments of the comprehensive decree against all hostile powers. The Bible uses large empires to hyperbolically represent the entire earth.
26 This is the purpose that is purposed concerning the whole earth, and this is the hand that is stretched out over all the nations.