Isaiah 9:11-12 Therefore the LORD raises against them adversaries from Rezin and spurs their enemies on, the Arameans on the east and the Philistines on the west; and they devour Israel with gaping jaws. In spite of all this, His anger does not turn away and His hand is still stretched out.
The Bible tells us Rezin is synonymous Damascus, Syria from Isaiah 7:8a “For the head of Aram is Damascus and the head of Damascus is Rezin…” They are also known as the Arameans. The Philistines are the equivalent to the area where the modern day Gaza Strip is located on the Mediterranean Sea southwest of Jerusalem.
God is going to use these two groups of people to judge Israel. As enemies of Israel, Syria and the Philistines are willing accomplices and instruments of God. Their destruction of Israel is with complete totality.
With this initial judgment God is not finished, He is just getting started. God has His hand ready to strike Israel again. The phrase “In spite of all this His anger does not turn away, and His hand is still stretched out” is noted three additional times in Isaiah 9:17, 9:21, and 10:4.
Judgment comes to a close in Isaiah 10:12. In total, Israel will go through a series of four judgments before God has finished His work.