פירוש על מלכים ב 25:1

In the ninth year of his reign. Of Tzidkiyohu.¹Which corresponds to Nevuchadnetzar's seventeenth year.—Radak

they built forts against it round about: These are towers that they built around the city to conquer it.

Siege towers. [Targum Yonoson] rendered כרקום [=works of siege].