Love is acting in the best interest of the one who is “Loved”.
Is it in the best interest of a Terrorist to allow them ample opportunities to slaughter the people they hate or is it in the Terrorists best interest to minimize their ability to express these evil impulses?
The only way this appears to be confusing is if a definition for “Love” is used that does not fit scripture very well, for instance "Love is taking actions that always please the one who is loved" or "Love can only be identified by how happy the loved person is after your say or do something that effects them"
Scripture says raising a child without discipline is “Hating” the child while a “Loving” parent will chastise the child for doing wrong, Scripture flatly declares that God disciplines his own because that is what all loving Fathers do as well.
Love is not a “feeling” of endearment or admiration for anyone, it also has nothing to do with whether a person is likable or insufferable; there is no command to feign an attraction or approval of anyone.
I am sure the money changers who got their butts kicked and their wares thrown all over the Temple did not “feel” very positive feelings at the time Jesus was publicly humiliating them, but they were better for having endured his discipline and experiencing shame appropriate to their actions.
Jesus loved them whether they loved his expression of that love or not.
Stopping evil that when practiced destroys the innocent and mocks the very existence of Justice is “in the best interest” of the one who commits the evil and all those who are victimized by their evil as well; there is no violation of the command to “Love your enemy” in such pursuits.
The violation would be possible only after the one bent on evil was stopped from doing his deed.
If the attitude toward the now captured and/or neutralized Terrorist is such that they do not deserve to hear the good news that there is a God who has made a way for their complete forgiveness, if we cannot view them as merely one more sinner in need of a Savior like everyone else, if we do not have the capacity to imagine the family of God with them as a member; it is then that we violate the command to “Love our enemy”.
Love is not a hindrance to Justice or Faith, it only hinders our ability to preserve resentment.