Would the WTS call it "murder" or "execution"? The WTS has several articles and talks on this scripture and applied it to Armageddon and the role jws would play.
*** w03 6/1 p. 20 par. 10 Stand Still and See the Salvation of Jehovah! ***
It was exactly as Jehovah had foretold: “You will not need to fight.” (2 Chronicles 20:17) This sets the pattern for Christians to follow when Jesus Christ moves in “to complete his conquest.” Meanwhile, they continue to fight evil, not with carnal weapons, but with spiritual ones. They thereby “keep conquering the evil with the good.”—Romans 6:13; 12:17-21; 13:12; 2 Corinthians 10:3-5.
*** w03 6/1 pp. 15-16 pars. 15-16 “Do Not Be Afraid or Be Terrified” ***
We read: “Pay attention, all Judah and you inhabitants of Jerusalem and King Jehoshaphat! Here is what Jehovah has said to you, ‘Do not you be afraid or be terrified because of this large crowd; for the battle is not yours, but God’s. . . . You will not need to fight in this instance. Take your position, stand still and see the salvation of Jehovah in your behalf. O Judah and Jerusalem, do not be afraid or be terrified. Tomorrow go out against them, and Jehovah will be with you.’”—2 Chronicles 20:15-17.
16 The people of Judah were assured that they would have no need to fight. Likewise, when God’s people are attacked by Gog of Magog, they will refrain from taking up arms in self-defense. Rather, they will “stand still and see the salvation of Jehovah” in their behalf.
*** w05 12/1 p. 6 Armageddon—A Happy Beginning ***
However, God’s earthly worshippers will not participate in the battle. The vision in Revelation chapter 19 indicates that only heavenly armies will share with Jesus Christ in the warfare. None of Jehovah’s Christian servants on earth will take part.—2 Chronicles 20:15, 17.
*** ka chap. 9 pp. 154-155 par. 19 The Post-Millennial Test of All Mankind ***
Choosing the side of Jehovah God, they let him make expression of his universal sovereignty and prove it to the misled disloyal ones. They let the battle be Jehovah’s and so do not assume to act as His executional forces and fight with lethal weapons. This displays, not only faith on their part, but also perfect integrity toward Jehovah God and his universal sovereignty. Let Him himself save them and destroy the disloyal ones! Trustfully they stand still and see the “salvation of Jehovah” in their behalf.—2 Chronicles 20:15-17.
*** w03 6/1 pp. 21-22 Stand Still and See the Salvation of Jehovah! ***
How Will God’s Servants React?
14 What will servants of God be expected to do once they come under attack? Again, the reaction of God’s typical nation in the days of Jehoshaphat sets the pattern. Note that its citizens were commanded to do three things: (1) take their position, (2) stand still, and (3) see the salvation of Jehovah. How will God’s people today act in harmony with these words?—2 Chronicles 20:17.
15 Take their position: Without wavering, God’s people will continue to hold to their position of active support for God’s Kingdom. They will continue to maintain their position of Christian neutrality. They will be “steadfast, unmovable” in their loyal service to Jehovah and will continue publicly to praise Jehovah for his loving-kindness. (1 Corinthians 15:58; Psalm 118:28, 29) No present or future pressure can shake them from this divinely approved position.
16 Stand still: Jehovah’s servants will not try to save themselves but will place their implicit trust in Jehovah. Only he is capable of rescuing his servants out of world chaos, and he has promised to do so. (Isaiah 43:10, 11; 54:15; Lamentations 3:26) Trusting in Jehovah will include trusting the modern visible channel that he has clearly been using for decades to serve his purposes. As never before, true Christians will then need to place their confidence in fellow worshipers authorized by Jehovah and his reigning King to take the lead. These faithful men will direct God’s people. Ignoring their direction could end in disaster.—Matthew 24:45-47; Hebrews 13:7, 17.
17 See the salvation of Jehovah: Salvation will be the reward for all those who hold to their position of Christian integrity and who trust in Jehovah for deliverance. Until the final hour—and to the extent they can—they will announce the arrival of the day of Jehovah’s judgment. All creation must know that Jehovah is the true God and that he has faithful servants on earth. Never again will there be the need for a prolonged controversy over the rightfulness of Jehovah’s sovereignty.—Ezekiel 33:33; 36:23.
(2 Chronicles 20:15-17) 15 Consequently he said: “Pay attention, all Judah and YOU inhabitants of Jerusalem and King Je·hosh ′ a·phat! Here is what Jehovah has said to YOU, ‘Do not YOU be afraid or be terrified because of this large crowd; for the battle is not YOURS, but God’s. 16 Tomorrow go down against them. There they are coming up by the pass of Ziz; and YOU will be certain to find them at the end of the torrent valley in front of the wilderness of Je·ru ′ el. 17 YOU will not need to fight in this instance. Take YOUR position, stand still and see the salvation of Jehovah in YOUR behalf. O Judah and Jerusalem, do not be afraid or be terrified. Tomorrow go out against them, and Jehovah will be with YOU.’”