The latter part of the verse expounds the former; God had made the Babylonians his hammer, to break other nations in pieces, now it was itself broken: the particle how may be understood either as expressing triumph and rejoicing, or admiration, or as inquiring how such a thing could be in the last sense. The next verse is an answer to this.
Related Commentaries of Jeremiah 50:23
Jeremiah 50:23
23 How is the hammer of the whole earth cut asunder and broken! how is Babylon become a desolation among the nations!