'Agent' in the Bible

behold (hear this), I will send for all the families of the north,’ says the Lord, ‘and I will send for Nebuchadnezzar king of Babylon, My servant [to enact My plan], and I will bring them against this land and against its inhabitants and against all these surrounding nations; and I will utterly destroy them and make them a horror and a hissing [that is, an object of warning and ridicule] and an everlasting desolation.