As God sets out to unfold his great eschatological working in and on behalf of Israel (12:1–9), he reminds us that he is the Creator of heaven and earth and that he also formed man’s spirit within him. Thus he has the absolute right and sovereign ability to do as he wishes. There is no power in heaven or earth that can deter him from accomplishing his purpose. Israel as a nation (not just the northern kingdom) will be restored, the nations will be judged, and God’s kingdom will be established.
The expression “on [or “in”] that day” occurs sixteen times in the last three chapters of Zechariah. The setting is in the last days, when God judges the nations, restores Israel, and establishes his kingdom on earth. The particular setting of this paragraph is the last and climactic siege of Jerus…