A prophecy of harsh, measure-for-measure justice is directed at the Ammonite nation. Although Ammon managed to escape the Babylonian forces that recently destroyed Jerusalem, their celebration will be remarkably short-lived. A new conqueror is destined to sweep in and seize their territory, bringing a devastating end to their joy [רד״ק, מצודת דוד]. The warning speaks to both the individual citizens and the collective spirit of the nation as a whole [רד״ק].
The land of Ammon is slated to be handed over to eastern peoples, though there are different views on exactly who these invaders will be. They might be the Chaldeans and Arameans attacking from the east [רש״י], or perhaps the rising empires of Media and Persia descending from the northeast [רד״ק, מצודת דוד]. Another approach suggests the invaders will be nomadic tribes emerging from the deserts beyond Ammon's borders [ביאור שטיינזלץ].
Whoever the invaders are, their arrival will not be a mere raid for quick plunder. Instead, they will claim the land as an absolute and permanent inheritance [מצודת ציון, רד״ק, מצודת דוד]. The enemy will firmly establish themselves, setting up both their grand structures and their everyday homes. There are varying perspectives on what these larger structures will look like. They are largely understood to be massive palaces and halls [רד״ק, מצודת ציון], with some noting that these will be central sites for idol worship. Building such monuments serves as a direct punishment for Ammon's gleeful reaction to the destruction of God's Temple in Jerusalem [מלבי״ם]. Another perspective suggests that the invaders will simply set up vast encampments of tents [ביאור שטיינזלץ]. Either way, the establishment of regular residential dwellings [מצודת ציון, ביאור שטיינזלץ] and the permanent occupation of the land act as a mirror punishment for Ammon gloating when the Israelites were forced into exile [מלבי״ם].
Once settled, the conquerors will fully exploit the nation's natural wealth. Vivid imagery of the enemy eating the local fruit and drinking the milk represents the total consumption of Ammon's agricultural produce and the looting of all its resources [רד״ק, מצודת דוד]. In a final reversal of fortune, while the foreign invaders feast on the bounty of the land, the Ammonites themselves will be driven out and forced into exile [מלבי״ם].