Charles Ellicott Commentary Amos 3:11

"Therefore thus saith the Lord Jehovah: An adversary [there shall be], even round about the land; and he shall bring down thy strength from thee, and thy palaces shall be plundered." — Amos 3:11 (ASV)

An adversary.— This rendering is preferable to “affliction” (Chaldean, Syriac). It is the subject of the following verb “bring down,” referring to Assyria, though not in express terms. The reading of the Septuagint, “O Tyre, your land around you is desolate,” is incoherent and confuses Tzăr with tzôr.

Your strength points mainly to the stronghold of Samaria, which the enemy was to bring down or reduce to ruins, but it may also include the chief warriors who were to be led away captive.