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The current US Department of Defense under Pete Hegseth is fundamentally altering what are normally known as the “rules of war.” This is understandably controversial and difficult, but it is also an issue within Christianity and the tradition known as the Just War.  Hegseth purports to be Christian; so, I assume he is familiar with biblical teaching on this subject and the doctrinal position known as the Just War. Let me explain.

Daivd Ignatius helps put this in context:  “For decades, West Point cadets have been assigned to read Michael Walzer’s book Just and Unjust Wars as a primer on what the military academy describes as ‘the ethical and moral dimensions of warfare.’  Defense Secretary Pete Hegseth didn’t attend West Point. He’s a Princeton grad who joined the National Guard and fought in Iraq and Afghanistan. But he wrote extensively about the rules of war before becoming secretary of defense — and his view was essentially the opposite of philosophers like Walzer. Instead of counseling careful norms of behavior, Hegseth railed at ‘the folly of international law, and the crazy maze of rules of engagement.’  Hegseth launched a frontal attack on the laws of war in his 2024 book, The War on Warriors. He wrote: ‘If our warriors are forced to follow rules arbitrarily and asked to sacrifice more lives so that international tribunals feel better about themselves, aren’t we just better off winning our wars according to our own rules?! Who cares what other countries think.’”  Hegseth built his career, in part, on challenging the rules of war. But these “rules,” many of which are rooted in biblical Christianity, are not arbitrary.  They have a moral and ethical basis—and must not be treated as trivial or “arbitrary.”

Arguably, the history of warfare is, in part, about the barbarity of killing and attempts to restrain it. Walzer explains that English knights refused to kill their prisoners at the Battle of Agincourt in 1415 partly because of “the dishonor that the horrible executions would reflect on themselves.” Gen. Erwin Rommel, a German general in World War II, disobeyed an order by Adolf Hitler, his commander in chief, to shoot enemy prisoners. A German soldier who refused to shoot prisoners was charged with treason and executed, Walzer notes.  “West Point students study Walzer because America has a tradition of valuing honor and lawful conduct in battle.”

Let’s examine Hegseth’s position and pronouncements through the lens of the Just War tradition?  Pacifism and activism are the two extremes on the war issue.  Pacifism says it is never right to use war as policy; activism says it is always right.  Throughout the history of the church, a mediating view, rooted in Scripture, has developed called the Just War tradition.  This tradition deems certain wars just and others unjust.   The challenge lies in discerning which wars are just.  Beginning with Augustine, a theologian from the fifth century, Christians have embraced the idea that specific criteria exist to determine whether a war and its conduct are considered “just.”   Thomas Aquinas in the 13th century and Reinhold Niebuhr in the 20th century further developed Augustine’s arguments.   What follows is a summary of the most widely accepted criteria for the just war tradition:

1. A Just Cause.  A just cause for the use of military force exists whenever it is necessary either to repel an unjust attack, to retake territory wrongly taken, or to punish evil.  An example of this criterion is Saddam Hussein’s invasion of Kuwait in 1990.  Ethically speaking, just war theorists argued that Saddam’s action was a flagrant case of aggression and therefore it was justifiable for the world community to repel this unjust aggression. Putin’s invasion of Ukraine was a blatant act of aggression.
2. Right Authority.  This criterion focuses on established, legitimate, and properly constituted authority using military force for a “just cause.”  In the United States this “right authority” consists in the powers granted to the President of the United States by the War Powers Act or by a congressional declaration of war.  In international affairs today, “right authority” might involve action by the UN Security Council authorizing the use of force.  The point of this criterion focuses on legitimate authority, not private individuals who wage war.
3. Right Intention.  This criterion stresses the end goal for the use of military force.  The aim must be, for example, to turn back or undo aggression and then to deter such aggression in the future.  The end for the use of force must be peace, not aggression or continued war.  Again, the Gulf War of 1991 offers an example of this just war criterion.  The world community had no aggressive aims against the territory or people of Iraq.  “Right intention” in this conflict meant rolling back Saddam’s aggression, establishing the peace of the Middle East and assuring that safeguards would protect that peace in the future.  The goal of the Ukraine conflict should be to roll back Russian aggression.
4. Proportionate Means.  As a criterion, this point centers on just means in the use of force; it must be appropriate to the goal.  Allowing aggression, for example, to stand is condoning an evil in itself and opening the door to yet further evil.  Therefore, any military force must be proportionate to the goal.  Using nuclear weapons, for example, would be disproportionate in rolling back aggression of a nation with no air force or navy.  Using chemical and biological weapons is another example of disproportionate means.
5. Last Resort.  This criterion involves the legitimate government using all diplomatic and foreign policy resources, including economic sanctions, to force the aggressive nation to pull back.  If the aggressor responds with intransigence and continued belligerence, the legitimate government has no choice but to use military force.  Again, the Iraq crisis of the 1990-1991 offers a classic example of this criterion: The allies used economic sanctions, diplomatic activity and personal diplomacy to alter Saddam Hussein’s aggressive actions against Kuwait.  He refused.  Therefore, just war advocates argue, the world community was just in rolling back his aggressive actions.  The US and Europe imposed severe sanctions on Russia, but to no avail.  So far, these sanctions have not thwarted Putin’s evil intentions.
6. Noncombatant Immunity.  This is the most difficult criterion for the just war position.  The military force used must be discriminate; it must follow the moral principle that seeks to protect noncombatants in a military strike or in a war.  Of course this means going to all ends to not attack intentionally civilians, not to bomb civilian neighborhoods and not to kill intentionally and indiscriminately the civilian population of an enemy. Vladimir Putin has totally disregarded this proposition.  He has wantonly and intentionally killed civilians and destroyed civilian infrastructure such as water plants and electricity girds in Ukraine.  Thousands of civilians are dead because of his brutality.

In summary, the just war position argues that military action must be only for a just cause and not to pursue personal aggrandizement, glory or vengeance.  Military operations require approval from a recognized authority, and they should also have a realistic possibility of achieving their goals.   The good that likely will result from the military action must outweigh the evil.  Such action must be a last resort after less violent approaches have failed.  Deliberate attacks on civilian populations are prohibited, and all possible steps must be taken to reduce casualties. Excessive or unnecessary force should not be used against soldiers or civilians.

The United States has a longstanding tradition of upholding honor and following legal standards in warfare, as laid out in its military code of justice.  This code is found in the Uniform Code of Military Justice (UCMJ), federal law applying to all service members, supplemented by the Law of War (International Humanitarian Law) for conduct in armed conflict, ensuring discipline and defining offenses like desertion, disobeying orders, and crimes against civilians, all enforced through courts-martial and commander’s actions, aiming for effective operations while upholding legal and ethical standards. These various standards reflect the Just War tradition.  Secretary of Defense Hegseth should spend some time with these documents, with Scripture and with the Just War tradition.

See David Ignatius in the Washington Post (8 December 2025); and James P. Eckman, Biblical Ethics, pp. 61-70.