The position of Jesus Christ regarding war, it is not clearly specified in the New Testament of the Bible. Jesus Christ always taught love and peace, to the point of telling us that we should even love our enemies. But the times Jesus Christ lived on earth, Israel was an occupied territory by the Roman Empire, and even as He makes some comments and references about it, His position was never a political or military one. To properly appreciate and understand the biblical position regarding war, we must look at the whole Bible and the teachings of God through many prophets, kings and military leaders. The Bible consists of the Old Testament and the New Testament. The Old Testament is full of instances where God Himself has instructed His people, Israel to go to war against its enemies. Furthermore, the manner in which those wars were to be conducted would be considered by today's men's standards, barbaric and criminal, since often God instructed Israel not only to kill the enemies (soldiers) but also their women, children and livestock, and burn down and destroy their homes and settlements, their crops and their lands. Things are different in the New Testament, where the emphasis is made on love, peace, in helping others and even sacrifice for them. And yet, we believe in one God who is the same, yesterday, today and forever, and who changes not.
Many Christians avoid reading and studying the Old Testament, other than perhaps the Book of Psalms, the Book of Proverbs, the Book of Isaiah, and a few other which makes very little if any reference to war. When wandering in the desert, after being freed from the slavery in Egypt, God has given His Laws to His people, Israel, and, again, many of the God given Laws were, by today's standards, cruel and barbaric.
One of the Ten Commandments is, "you shall not murder". Unfortunately, biased readers of the Bible interpret the word murder in a convenient and "politically correct" manner, and find no reason at all to take the life of another human being. That is being taken totally out of context and true meaning, since the Commandment prohibits the intentional, premeditated and unjustified taking of an innocent person's life. Nowhere in the Bible, Old Testament and New Testament, is self defense prohibited, even to the point of taking the life of an aggressor as a last resource.
It is worth mentioning that Jesus Christ was tortured and crucified not by the Jews, since there was nothing according to God given Laws that Jesus has violated to the point of deserving the death penalty. That is the reason Jesus Christ was taken to the Romans and it was the Romans who put Jesus Christ on the cross, even as Jesus Christ was found innocent by the Roman Procurator Pontius Pilate.
Back to the issue of love and war, if you love someone, you will do whatever you can to protect him/her, even if protection means taking the attacker's life as a last resort to save your loved one's life. For a time, even here in the United States, killing in self defense was not considered a crime, until the liberal cancer persuaded the Courts that even the criminal has rights and if killed while committing a crime, the killer is charged with homicide or manslaughter, and most likely spend the rest of his/her life in prison. As stupid and unjust as it sounds, criminals have more rights that law abiding citizens.
On a larger scale, a nation has all the right in the world to defend itself against enemies that not only have sworn to destroy the nation and kill its citizens, but have actually done that, both on its territory and abroad. When the enemy has publicly declared that it will do whatever they can to harm you and your people and destroy your nation, and has supported their threats with action, it is completely reasonable to take preventive measures, even to the point of hunting them down and eliminating them.
And that is what the Unites states must do. We have no other choice, because the enemy will never sit down to negotiate peace, because the enemy doesn't want peace but the destruction of America and the killing of innocent men, women and children. There is only one option left, and that is, extermination. It is a matter of kill or be killed.