This is how you are to treat all the cities that are far away from you and do not belong to the nations nearby.
15. Thus shalt thou do unto all the cities. An exception is introduced, that the Jews should not apply the common laws of war to the Canaanitish nations, with respect to whose extermination the sentence had passed. Addition in Fr., “et l’execution commise aux enfans d’Israel;” and its execution committed to the children of Israel.
They are here directed what method to take in dealing with the cities (these only are mentioned, Deu 20:10, but doubtless the armies in the field, and the nations they had occasion to deal with, are likewise intended) upon which they made war.
Commenting on Deuteronomy 20:10-20
Thus shalt thou do unto all the cities which are very far off from thee,.... As all such were reckoned that were without the land of Israel, even all in their neighbouring nations, the Moabites, Edomites, Ammonites, Syrians, &c. for the children of Israel never went to war with any very distant nations, unless they came unto them and invaded them; nor did they seek...