Peter Jenkins, Britain’s former representative on the International Atomic Energy Agency, has caused some controversy in a speech he gave at Warwick University where he stated:
Israelis don’t practise an eye for an eye and a tooth for a tooth, they practise ten eyes for an eye and ten teeth for a tooth.
The idea that a just war requires the use of force to be proportionate seems to be a Christian notion and not a Jewish notion. 
The Jewish Chronicle reports that in response to Jenkins’ comments, Jonathan Sacerdoti, director of the Institute for Middle Eastern Democracy, informed the audience that Jenkins’ speech was ‘laced with its subtle attempts at antisemitism, masked behind polite diplomatic chatter.’  The Community Security Trust, an organisation that represents British Jewry to Police, Government and media on antisemitism and security, accused Jenkins of ignorance.
Like many statements that are often used to attack Israel, while devoid of any context, there is an element of truth in Jenkins’ remark. Michael Broyde of the Emory University School of Law explains that while it is ‘terribly disquieting’ and ‘deeply uncomfortable’ to him:
Jewish law has no ‘real’ restrictions on the conduct of the Jewish army during wartime, so long as the actions being performed are all authorized by the command structure of the military in order to fulfill a valid and authorized goal and do not violate international treaties.
The conclusion is stark: it is international treaties, not Jewish law that leads to the proportionality requirement of the conduct in war. While conventions external to Jewish law, but mutually agreed by the combatants, would be binding on all Jewish adherents, ‘Jewish law has few, if any, rules of battle.’
Elliot Dorff, Rabbi and professor of Jewish theology at the American Jewish University comments that ‘the principle of proportionality is not nearly as clear and authoritative a tenet in Judaism as it is in Catholicism.’ Even more firm in his statement is Yishai Kiel of the Department of Talmud at the Hebrew University of Jerusalem. He points out that there is a ‘total absence of moral issues relating to warfare in the classical rabbinic statement regarding the laws of war in the eighth chapter of tractate Sotah, including the Mishnah, and the Tosefta, and both Talmuds.’ Dorff points out that it is not even entirely clear as to whether Jewish law ‘requires any distinction between combatants and noncombatants even in the conduct of war.’
Moreover, in advance of war, Rabbi Bleich, Professor of Jewish Law and Ethics at the Benjamin N. Cardozo School of Law, in a conclusion largely agreed with by the eminent Just War theorist, Michael Walzer, said:
Not only does one search in vain for a ruling prohibiting military activity likely to result in the death of civilians but, to this writer’s knowledge, there exists no discussion in classical rabbinic sources that takes cognizance of the likelihood of causing civilian casualties in the course of hostilities legitimately undertaken as posing a halakhic [Jewish legal] or moral problem.
Numerous Jewish laws (the discussion of which is outside the scope of this article) exist as to which wars are optional, which are commanded, and which are obligatory to fight. There are laws as to what must occur before a war. Notably, according to Maimonides, a great authority on Jewish law, it is obligatory to seek peace before a war is commenced:
One does not wage war with anyone in the world until one seeks peace with him…. as it says [in the Torah], ‘When you approach a city to wage war, you shall [first] call to it in peace.’
A traditional Jewish greeting is ‘Shalom.’ This translates as ‘peace,’ but as Michael Walzer explains, ‘Shalom has a more local and immediate meaning, “not war,” as in the biblical command to “proclaim peace.”’ Yishai Kiel is explicit: ‘the “Call for Peace”…[is] ultimately designed to avoid the bloodshed concomitant with the state of war.’
Moreover, the important thirteenth century Jewish scholar Nahmanides tells Jews:
God commanded us that when we lay siege to a city that we leave one of the sides without a siege so as to give them a place to flee to. It is from this commandment that we learn to deal with compassion even with our enemies even at time of war.
Jewish law prohibits wanton destruction. For as it says in the scripture:
When thou shalt besiege a city a long time, in making war against it to take it, thou shalt not destroy the trees thereof by wielding an axe against them: for thou mayest eat of them, and thou shalt not cut them down. (Deuteronomy 20:19)
In his codification of this prohibition of cutting down fruit-bearing trees, Maimonides expanded it to include other items: tearing clothes or demolishing a building, as examples, would both transgress the command ‘You shall not destroy.’
Rabbi Bleich informs us that in Jewish law an assessment must be made as to ‘whether a proposed war is indeed necessary and whether it will be successful in achieving its objectives.’ It is ‘only when the lives preserved are greater in number than the lives whose loss may be anticipated as a result of armed conflict’ that ‘the need to eliminate a potential aggressor is an imperative causus belli that renders even preemptive war permissible.’ He notes, ‘The justification of war in such circumstances is the saving of lives, not the punishment of the enemy.’
When it comes to nuclear war, the late Chief Rabbi, Lord Jakobovits discussed the matter some fifty years ago:
In view of this vital limitation of the law of self-defense, it would appear that a defensive war likely to endanger the survival of the attacking and the defending nations alike, if not indeed the entire human race, can never be justified. On the assumption, then, that the choice posed by a threatened nuclear attack would be either complete destruction or surrender, only the second may be morally vindicated.
What is clear from Jakobovits’s argument that leads to his conclusion is that in his opinion, the immorality of the use of nuclear weapons in Jewish law is largely because the survival of both sides are endangered, for as he earlier says:
So long as wars were limited and it was likely that the belligerents would survive and one would emerge victorious, the basic right to arm and to wage war was clearly asserted by the law of self-defense, whether what was to be defended were lives or moral values. But if both the lives and the values to be defended may, as now appears possible, themselves be destroyed together with the aggressor in the exercise of self-defense, the right to resort to it is questionable.
It is true, as Peter Jenkins suggested, that the concept of proportionality in war in the way that we understand it in the modern day owes much to Christian thought, specifically to Aquinas in the thirteenth century, as opposed to Jewish thought. The reason why Jews did not historically focus on this area is obvious – and it was pointed out by the late Rabbi Louis Jacobs: ‘For 2,000 years Jews had no state of their own, so that the whole question was academic.’ Michael Walzer elaborated on this point: ‘Jews are the victims, not the agents, of war. And without a state or an army, they are also not the theorists of war.’
The ethics of war are considered both by the State of Israel and by scholars of Orthodox Jewish law. In a meeting of the Orthodox Forum held in March 2004, a conclusion was as follows:
The committee believed that discussions about how Judaism conceives the justification for war and the conduct of war should not be held in a vacuum; they should not take place exclusively on the plane of [Jewish legal and traditional non legal Jewish narrative] sources. Rather, religious explorations must engage secular ethical perspectives and secular legalities, as well as perspectives promulgated by Christianity in its quest for a definition of ‘Just War.’ We need to place Jewish tradition in conversation with general moral sensibilities and international regulations.
When it comes to the value placed on human life, rather than Jenkins’ argument that Israelis ‘practise ten eyes for an eye and ten teeth for a tooth,’ one can consider what occurred in practice: last year the Israeli government agreed to free 1,027 prisoners, including some with blood on their hands, in exchange for Gilad Shalit, a single captured Israeli soldier.
The Israeli Defence Force (IDF) have a code of ethics. The Spirit of the IDF is drawn from a number of sources including ‘The tradition of the Jewish People throughout their history’ and ‘Universal moral values based on the value and dignity of human life.’ This code includes the idea of ‘Purity of Arms.’ The relevant clause I copy below:
The IDF servicemen and women will use their weapons and force only for the purpose of their mission, only to the necessary extent and will maintain their humanity even during combat. IDF soldiers will not use their weapons and force to harm human beings who are not combatants or prisoners of war, and will do all in their power to avoid causing harm to their lives, bodies, dignity and property.
I leave the last word to Michael Broyde:
We all pray for a time where the world will be different – but until that time, Jewish law directs the Jewish state and the American nation do what it takes (no more, but no less, either) to survive and prosper ethically in the crazy world in which we live.
Bleich, David J. 1983, ‘Preemptive War in Jewish Law’, TRADITION: A Journal of Orthodox Thought, Vol. 21, Number 1, Spring: 3-41.
Broyde, Michael J. 2007, ‘Just Wars, Just Battles and Just Conduct in Jewish Law: Jewish Law is Not a Suicide Pact!’, in Lawrence Schiffman and Joel B. Wolowelsky (Eds.), War and Peace in the Jewish Tradition, New York: Yeshiva University Press: 1-43.
Dorff, Elliot N. 1991, ‘Bishops, Rabbis, and Bombs’, in Confronting Omnicide: Jewish Reflections on Weapons of Mass Destruction, edited by Daniel Landes, Northvale, New Jersey: Jason Aronson Inc.: 164-195.
‘Ethics’, Israeli Defence Forces. Available on line at http://dover.idf.il/IDF/English/about/doctrine/ethics.htm (Accessed November 8, 2012)
‘Israeli court rejects Shalit swap delay bid’, 2011, BBC, October 17. Available online at http://www.bbc.co.uk/news/world-middle-east-15338829 (Accessed November 8, 2012).
Jakobovits, Immanuel 1962, ‘Rejoinders’, TRADITION: A Journal of Orthodox Thought, Vol. 4, Number 2, Spring: 198-205.
Kiel, Yishai 2012, ‘The morality of war in rabbinic literature: The Call for Peace and the Limitation of the Siege’, in War and Peace in the Jewish Tradition: From the biblical world to the present, edited by Yigal Levin and Amnon Shapira, Abingdon, Oxon: Routledge: 116-138.
Kimelman, Reuven 1991, ‘A Jewish Understanding of War and Its Limits’, in Confronting Omnicide: Jewish Reflections on Weapons of Mass Destruction, edited by Daniel Landes, Northvale, New Jersey: Jason Aronson Inc.: 82-99.
Leventer, Herb 2007, ‘Philosophical Perspectives on Just War’, in Lawrence Schiffman and Joel B. Wolowelsky (Eds.), War and Peace in the Jewish Tradition, New York: Yeshiva University Press: 45-92.
Peli, Pinchas H. 1991, ‘Torah and Weapons of Mass Destruction: A View from Israel’, in Confronting Omnicide: Jewish Reflections on Weapons of Mass Destruction, edited by Daniel Landes, Northvale, New Jersey: Jason Aronson Inc.: 69-81.
Scheinman, Anna 2012, ‘A just war? That’s just not Jewish, says ex-envoy’, The Jewish Chronicle Online, October 25. Avilable online at http://www.thejc.com/news/uk-news/88067/a-just-war-that%E2%80%99s-just-not-jewish-says-ex-envoy (Accessed November 8, 2012).
Shatz, David 2007, ‘Introduction,’ in Lawrence Schiffman and Joel B. Wolowelsky (Eds.), War and Peace in the Jewish Tradition, New York: Yeshiva University Press: xiii-xxxviiii.
Walzer, Michael 1996, ‘War and Peace in the Jewish Tradition’, in The Ethics of War and Peace: Religious and Secular Perspectives, edited by Terry Nardin, Princeton, New Jersey: Princeton University Press: 95-114.
 Scheinman 2012.
 Scheinman 2012.
 Scheinman 2012.
 Broyde 2007, p. 7.
 Broyde 2007, p. 7.
 Dorff 1991, p. 180.
 Kiel 2012, p. 132.
 Dorff 1991, p. 176.
 Walzer 1996, p. 108.
 Bleich 1983, p. 19.
 Maimonides, Hilkhot Melakhim 6:1 cited in Broyde 2007, p.19.
 Walzer 1996, p. 96.
 Kiel 2012, p. 125.
 Broyde 2007, p. 21.
 Peli 1991, p. 73. (NB. In Peli’s article the reference is incorrectly provided as Deuteronomy 20:10. I have used the correct reference.)
 Maimonides, Hilkhot Melakhim 6:10 cited in Kimelman 1991, p. 90.
 Bleich 1983, p.25.
 Jakobovits 1962, pp. 201-2.
 Leventer 2007, p. 51.
 Jacobs, Louis 1973, What Does Judaism Say About…? New York: Quadrangle: p.228 cited in Dorff 1991, p. 171.
 Walzer 1996, p. 96.
 Shatz 2007, pp. xiii-xiv.
 ‘Israeli court rejects Shalit swap delay bid’, 2011.
 Broyde 2007, p. 31.