Jas 4, 2 You fight and wage war

(Jas 4, 2) You fight and wage war
[2] You covet but do not possess. You kill and envy but you cannot obtain; you fight and wage war. You do not possess because you do not ask.

(CCC 2317) Injustice, excessive economic or social inequalities, envy, distrust, and pride raging among men and nations constantly threaten peace and cause wars. Everything done to overcome these disorders contributes to building up peace and avoiding war: Insofar as men are sinners, the threat of war hangs over them and will so continue until Christ comes again; but insofar as they can vanquish sin by coming together in charity, violence itself will be vanquished and these words will be fulfilled: "they shall beat their swords into plowshares, and their spears into pruning hooks; nation shall not lift up sword against nation, neither shall they learn war any more" (GS 78 § 6; cf. Isa 2:4). (CCC 2310) Public authorities, in this case, have the right and duty to impose on citizens the obligations necessary for national defense. Those who are sworn to serve their country in the armed forces are servants of the security and freedom of nations. If they carry out their duty honorably, they truly contribute to the common good of the nation and the maintenance of peace (Cf. GS 79 § 5). (CCC 2311) Public authorities should make equitable provision for those who for reasons of conscience refuse to bear arms; these are nonetheless obliged to serve the human community in some other way (Cf. GS 79 § 3). (CCC 2313) Non-combatants, wounded soldiers, and prisoners must be respected and treated humanely. Actions deliberately contrary to the law of nations and to its universal principles are crimes, as are the orders that command such actions. Blind obedience does not suffice to excuse those who carry them out. Thus the extermination of a people, nation, or ethnic minority must be condemned as a mortal sin. One is morally bound to resist orders that command genocide. (CCC 2314) "Every act of war directed to the indiscriminate destruction of whole cities or vast areas with their inhabitants is a crime against God and man, which merits firm and unequivocal condemnation" (GS 80 §3). A danger of modern warfare is that it provides the opportunity to those who possess modern scientific weapons especially atomic, biological, or chemical weapons - to commit such crimes.