[2] The Synchronistic King List[i 2] identifies his Babylonian contemporary with Adad-šuma-uṣur, his eventual nemesis.
Grayson[3] and others[4] have speculated that this was with the tacit assistance of Adad-šuma-uṣur, but there is currently no published evidence to support this theory.
Ninurta-apal-Ekur’s purpose for being in Babylonia is also unknown, whether a political refugee or an administrator of the Assyrian held portion.
Meanwhile, the Synchronistic History[i 3] continues, Ninurta-apal-Ekur had “mustered his numerous troops and marched to conquer Libbi-ali (the city of Aššur).
But [...] arrived unexpectedly, so he turned and went home.” As Grayson points out, this passage is open to various interpretations,[3] only one of which is that the missing name could have been that of Enlil-kudurrī-uṣur, released by his captor to sow confusion amongst his northern foes.