Jeremiah 21:10 [God speaking through Jeremiah]
"For I have set My face against this city for adversity and not for good," says the Lord. "It shall be given into the hand of the king of Babylon, and it shall burn with fire."
In Deut. 17:18-20 it was stated that the king was responsible for learning and upholding the Law. He was to read the Law every day. So in not following or upholding the Law, as instructed in Deuteronomy 17, the king now has the responsibility for the destruction of Jerusalem, and the fall of Judah. God is holding him accountable.