מלכים ב כד:ט פירוש: Metzudat David, רש״י ורלב״ג

after 3 years.

He awoken the hearts of the armies of the Chaldeans etc..., so that they will bring war to Judah.

According to the [extended] timespan of the events, therefore it went back and said "He sent them", for this was typical (grammar) for scriptures.