Actually God was speaking about moving the King of Assyria by putting a hook in his nose and bridle on his lips.
6 And Isaiah said unto them, Thus shall ye say unto your master, Thus saith the Lord, Be not afraid of the words that thou hast heard, wherewith the servants of the king of Assyria have blasphemed me.
7 Behold, I will send a blast upon him, and he shall hear a rumour, and return to his own land; and I will cause him to fall by the sword in his own land.”
God can move the saved and the unsaved to fulfill His will, purpose or desire.