Assyria was simply an unwitting tool in Yahweh's hand that He would use to accomplish His purposes (cf. Hab. 1:12-17). This pericope is one of the greatest revelations of the relation between heaven and earth in the Bible.127
10:5-6 Assyria was like a rod in God's hand; He controlled her actions. He would send her to discipline godless Judah against whom God's fury burned, "to capture booty and to seize plunder"(v. 6, the meaning of Maher-shalal-hash-baz's name, 8:1, 3). However, Assyria was in for woe herself (cf. v. 1) because she failed to acknowledge that she was under the sovereign authority of Yahweh.
10:7 Assyria did not consciously serve God. She planned to pursue her own selfish purposes and to destroy many nations to expand her own empire. She mistakenly thought she was sovereign.
10:8-11 Assyria, in her unrealistic pride, boasted, in the person of her king, that her princes were the equivalent of kings, so great was their authority. She assumed that the cities of Judah were the same as the cities of other nations, namely, without Yahweh's special concern. She mistakenly thought that Judah's God was just another god (cf. 2 Kings 18:33-35). Therefore she planned to do to Judah and Jerusalem just as she had done to other nations and their great cities. In each of the three pairs of cities listed (v. 9), the first is farther southwest than the second. The prophet portrayed the Assyrian king as thinking, "I took that one, so I can take this one."
