"Fallen, fallen is Babylon; and all the carved images of her gods he has shattered to the ground" (21:9). Isaiah saw a vision of the wilderness/desert near the sea, and in this vision, another empire had fallen: Babylon the great. Isaiah wept to see the human suffering caused by war: riders on horses, swords, “the press of battle,” the inevitable refugees fleeing the violence (v14-15). Even though the conquering Assyrians were also God’s hand of judgment, Isaiah grieved the situation; “the destroyer destroys” (v2).
God gives us “a stern vision” (v2) to warn us about the consequences of sin, personally and corporately. He comes not to destroy, but to save and give us abundant life.