Charles Ellicott Commentary Zechariah 12:9

"And it shall come to pass in that day, that I will seek to destroy all the nations that come against Jerusalem." — Zechariah 12:9 (ASV)

Seek. —This word is only twice used of God, here and in Exodus 4:24, where He sought to slay Moses: i.e., He expressed His determination to do so, but for certain reasons did not carry it out. So in this case He would have utterly destroyed the nations: that is, have given the Jews complete victory over them, but for Israel’s sin. (Compare the case of the Canaanites, Joshua 23:5; Joshua 23:12–13.)