The cup of God's anger is poured out, initiating a devastating chain of disasters destined to strike various nations. This wave of judgment strikes Jerusalem first, as the city was destined to face ruin before Egypt and the surrounding empires [מצודת דוד, מלבי״ם]. The devastation brought by Nebuchadnezzar, the king of Babylon, began in Jerusalem during the fourth year of Jehoiakim's reign, and only later spread outward to consume other nations [רד״ק].
The punishment falls heavily upon the royal leadership, striking multiple kings. This reflects the tragic sequence of monarchs who suffered through the unfolding disaster one after the other, specifically Jehoiakim, Jehoiachin, and Zedekiah [רד״ק]. Alternatively, while only one monarch ruled at any given time, the sons of the king also carried the royal title and shared in the same severe judgment [מצודת דוד].
The reality of the desolation is presented as a present, tangible ruin, existing on that very day. The primary approach among commentators is that Jeremiah recorded his prophecies after the destruction had already occurred. Therefore, he captures the desolate state of the land exactly as it was visibly witnessed at the time of his writing [רש״י, מצודת דוד, ביאור שטיינזלץ]. Another perspective suggests that the emphasis on the present day serves to guarantee that the ruin would be absolute, clear, and undeniable [ביאור שטיינזלץ].