Marty, the CCC is not obedient (and never has been) to Jesus' express and clear teaching on love, especially love of enemy.

For a Christian, God is the author of Natural Law. As God is love, then Natural Law rests upon this universal and unchanging dynamic.

Killing someone in war, against his will, would not respect this dynamic and would, therefore, have no appeal to Natural Law for justification.

There is no such thing as controllable war; it does not always proceed according to plan. This is established fact, particularly in the age of mechanized and digital warfare. Non-combatants inevitably are killed, including children, even those in the womb. Those who accept the theory of Just War cannot divorce themselves, either intellectually or morally, from this so-called "collateral damage".  A peculiar position for the Catholic Church, given its uncompromising teaching against abortion on the ground that human life is sacred.