Deuteronomy 20:20

20 Only, the tree, which thou knowest that it [is] not a fruit-tree, it thou dost destroy, and hast cut down, and hast built a bulwark against the city which is making with thee war till thou hast subdued it.

Deuteronomy 20:20 Meaning and Commentary

Deuteronomy 20:20

Only the trees which thou knowest that they be not trees for
meat Which might be known not only by their not having fruit upon
them, but by other tokens, and even at a time of year when there was no fruit on any, which might be sometimes the season of a siege:

thou shalt destroy and cut them down;
if so to do was of any disservice to the enemy, or of any service to them, as follows; they had a liberty to destroy them if they would:

and thou shall build bulwarks against the city that maketh war, until
it be subdued;
build bulwarks of the trees cut down, and raise batteries with them, or make machines and engines of the wood of them, to cast stones into the city to annoy the inhabitants of it, in order to make them surrender, and until they do it. All this may be an emblem of the axe being to be laid to fruitless trees in a moral and spiritual sense; and of trees of righteousness, laden with the fruits of righteousness, the planting of the Lord, being preserved and never to be cut down or rooted up; see ( Matthew 3:10 ) ( Isaiah 60:3 ) ( Matthew 15:13 ) .

Deuteronomy 20:20 In-Context

18 so that they teach you not to do according to all their abominations which they have done to their gods, and ye have sinned against Jehovah your God.
19 `When thou layest siege unto a city many days, to fight against it, to capture it, thou dost not destroy its trees to force an axe against them, for of them thou dost eat, and them thou dost not cut down -- for man's [is] the tree of the field -- to go in at thy presence in the siege.
20 Only, the tree, which thou knowest that it [is] not a fruit-tree, it thou dost destroy, and hast cut down, and hast built a bulwark against the city which is making with thee war till thou hast subdued it.
Young's Literal Translation is in the public domain.