My sister in law is a devout Catholic. I mean really devout. I asked her how she could vote for Obama when he was for late term abortions, the kind where the Dr takes a knife and severs the baby’s spinal cord.
She replied, even though she was against abortion, she was against war, and killing of people in other countries. For her, she wanted the war to end and that is why she voted for Obama.
That is their logic.
She did not get what she wanted. Likewise, Republican presidents do not really work to end abortion.
War can be morally justifiable. It's not a Catholic position to be "against war" in absolutely all circumstances. Whether a particular war is morally justifiable can be arguable, of course.
Abortion -- a direct, intended, mortal attack on an innocent child -- is never morally justifiable.