In Context

15 Thus shalt thou do to all the cities which are very distant from thee, which are not of the cities of these nations.

16 But of the cities of these people which the LORD thy God doth give thee for an inheritance, thou shalt save alive nothing that breatheth:

17 But thou shalt utterly destroy them, namely, the Hittites, and the Amorites, the Canaanites, and the Perizzites, the Hivites, and the Jebusites, as the LORD thy God hath commanded thee:

18 That they may not teach you to do after all their abominations which they have done to their gods; so would ye sin against the LORD your God.

19 When thou shalt besiege a city a long time in making war against it to take it, thou shalt not destroy the trees of it by forcing an ax against them; for thou mayest eat of them: and thou shalt not cut them down (for the tree of the field is man's life) to employ them in the siege:

20 Only the trees which thou knowest that they are not trees for food, thou shalt destroy and cut them down; and thou shalt build bulwarks against the city that maketh war with thee, until it shall be subdued.

Deuteronomy 20:18 in Other Translations