A commentator in an article in a Christian newspaper asked the question, with respect to Iraq: "What would Jesus do?" He gave and enlarged upon a number of answers which, summed up by him, indicated that Jesus' actions would be counter-intuitive, sacrificial, and non-violent. Here are his answers (italics), but with different interpretations.
Jesus would hold his fire. The usual example of Peter cutting off the guy's ear was used, with Christ's assertion that those who live by the sword will die by the sword. The commentator did not mention that only hours before Peter's action Christ at the "Last Supper" instructed his disciples to secure swords, even if they had to sell some of their clothing to do so (Luke's account). Jesus even emphasized the point by reminding them that whereas he had once sent them out without purse, bag, or sandals, the time had come for them to arm themselves. The Romans and Temple guards lived by the sword and eventually died by it. Christians still live today, 2,000 years later, not because their forbears lived by the sword, but because they refused to die by the sword.
Jesus would encourage creative non-violent resistance to evil. The "sermon on the mount" (words) was used by the writer to emphasize Christian pacifism. All four gospel-writers vividly describe Jesus' violent expulsion from the Temple of those who defiled it (actions, not words). John painstakingly described Jesus making a whip and using it to drive "all" from the temple, including sheep, goats and people. He upturned the moneychangers' tables and generally wrecked the place, with a degree of anger that can only be imagined. Matthew quotes Jesus in another episode as saying: "Do not think that I have come to bring peace on earth; I have not come to bring peace, but a sword." Plain common sense indicates that there will never be peace between those espousing good (believers) and those engaging in evil, exemplified in Iraq's Saddam. Jesus knew this and was no pacifist. The peace of the Bible is that which exists between God and believer, not between believers and non-believers, whether bellicose or quiet.
Jesus would walk into the middle of a battlefield as a human shield for both sides, imploring combatants to see other human beings as brothers and sisters. Anyone foolish enough to do this could be shot dead on the spot by either side. This approach supposes that bloodthirsty tyrants actually care about people, or that people of goodwill should not suspect foul play. This might work in Utopia; but, then, in Utopia, by definition, it would not be needed. This is a dangerous world. In any case, how could one man be a "human shield" for thousands?
Jesus would explore questions of justice and equity that spawn generation after generation of wars. The commentator quoted James: "The wisdom from above is first pure, then peaceable… ." James, however, was writing to the church, which, then as now, included members "at war" with each other over disagreements of doctrine, behavior, the use or non-use of the pipe organ, etc. He was not writing with respect to the rest of the world, obviously, where non-believers were not even availed of James' wisdom. Justice and equity are relative terms, anyway, subject to differing cultures and laws. For instance, an Arab woman bearing a child out of wedlock is subject to death, while in this country illegitimacy is practically glorified. If the nations that brainwash their young people into becoming suicide/homicide bombers are not discouraged, then, God help us all. These people choose to live and die by the sword, just as Jesus noted, but why should the innocent suffer?
Jesus would pray for his enemies, as he did from the cross. Jesus prayed for his enemies to be forgiven in their ignorance, not to somehow change into nice guys in the twinkling of an eye and let him go. The commentator asked how a believer can kill someone for whom he is praying. Not until one looks down the barrel of a gun pointed at him can he find out, especially if he has a family that needs him and/or contemplates the threat to their freedom, including the freedom of worship. The suspicion here is that he'll pull the trigger. Ask Christian war veterans.
Jesus would get in the face of religious leaders…and challenge the corruption of God's message for the sake of convenience and control. That may be fine for America, though preachers aren't exactly oiling their AK-47s, but precisely what religionist is going to get in the face of a Saddam, Kim Jong Il, Fidel Castro, Osama bin Laden, Khatami, Qaddafi (at least until recently), or any of the Arab royalty (take your choice)? Muslim countries may be ruled by religious leaders, but not all countries are. In any case, what would be the difference? Murder is murder is murder, whether ordered by atheistic monsters or religious leaders.
Religious leaders have spouted for so long about the love of God (which no one doubts) in such a la-la-land sense that they've turned Jesus (and by extension, believers) into some kind of wimp, a hand-wringing, cliché-babbling, "can't we all just get along," pathetic creature groveling before butchers. Jesus, fearing for his life during his ministry, was tough as nails (proven by the torture he endured) and told his followers to emulate him, physically if need be, while carrying out his commission. That's called "tough love," and Christendom had better take heed. This nation, while not Christian, probably embodies Christian values more than any other and must be militarily superior to any other nation or consortium of nations in a world that's mostly pagan and becoming more so every day. "Might makes right" is universally wrong, but "right makes might" is rarely accomplished, since "right," especially among religionists, usually means, in Cold War parlance, "better red than dead," a lethal compromise with the devil that induces weakness, not might.
As for so-called preemptive war, it should be remembered that FDR was aiding England long before the United States entered WWII against Germany. The only thing better than turning the other cheek is removing the need for doing it. That may sound harsh, but "survival of the fittest" is a natural law, and natural laws came with the Creation.