The Israelites grew deeply arrogant, boasting of their military successes and crediting their victories entirely to their own strength [אבן עזרא, רד״ק]. In a direct response to this pride, God issues an absolute decree [מלבי״ם]. He will raise up a foreign nation, identified as the king of Assyria and his army, to attack them [רד״ק]. This creates a sharp, ironic reversal. The Israelites had proudly bragged about destroying their enemies, but now they will be the ones who are completely pushed down and oppressed [אבן עזרא, מצודת ציון].
The coming invasion will sweep across the entire land, leaving no area untouched. The enemy will crush the nation from the northern road leading to the city of Hamath [מצודת דוד], all the way down to the southern border at the stream of the Arabah, understood as either the Sea of the Arabah or the Brook of Egypt in the southwest [רש״י, רד״ק]. The mention of these specific boundaries carries a deeper message. These were the exact borders of the kingdom that had been recently expanded during the era of Jeroboam II. The prophet highlights a painful truth. The very territories the Israelites conquered with the help of God, while falsely claiming the glory for themselves, will now become the exact stage for their defeat. From these same expanded borders, they will be completely overrun and forced into exile by Assyria [רד״ק, מלבי״ם, ביאור שטיינזלץ].