John Wesley on Isaiah 17:2

Aroer - Of that part of Syria, called Aroer, from a great city of that name. These cities were possessed by the Reubenites and Gadites, whom Tiglath - pilneser carried into captivity, 1Chron 5:26. These he mentions here, as he doth Ephraim in the next verse, because they were confederate with Syria against Judah. Afraid - Because the land shall be desolate, and destitute of men who might disturb them.