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Modern Warfare: When Is Intervention Moral?

Three days after the world celebrated the start of a new decade, the phrase “World War III” was trending on Twitter. On 3rd January 2020, General Qasem Soleimani, one of the most senior military commanders in Iran, was killed by a targeted drone attack directly ordered by the President of the USA Donald Trump. The fall-out terrified the world. Iran’s President Hassan Rouhani immediately respond saying “The great nation of Iran will take revenge for this heinous crime”, sparking fears of an all-out war. On 5th January, US President Donald Trump tweeted “… if Iran strikes any Americans, or American assets, we have targeted 52 Iranian sites… some at a very high level & important to Iran & the Iranian culture…”, followed up with a Tweet the following day that read “…should Iran strike any U.S. person or target, the United States will quickly & fully strike back & perhaps in a disproportionate manner”. As many in the media pointed out, both targeting cultural heritage sites, and disproportionate retaliation, are international war crimes. On 7th January, 50 people were killed in a stampede at General Soleimani’s burial in Iran. And then on 8th January, Iran launched missile attacks on two air bases housing US forces in Iraq.

The ethics of modern warfare and military intervention is complex, challenging and constantly changing, as weapons develop, geopolitical forces evolve, and international relationships become increasingly intertwined. But it is in times like these that an ethical framework for warfare is vital, as countries and leaders figure out which military actions are moral and just, and which are not.

So how can we begin to assess which military actions are moral?

As we shall see shortly, a lot of the Western ideas around ethical warfare find their roots in the writings of the Early Christian Church Fathers. I would argue that Christianity has provided some important foundational principles of the ethics of warfare, that have stood the test of time (and the evolution of warfare), and that are worth looking into, regardless of one’s own religious beliefs.

My aim with this article is to unpack some of these principles, and then to apply them to the current military tension between USA and Iran.

Jesus was a Peace-Maker, but not a Pacifist

Before going into the ethics of just warfare, it is worth mentioning the poles of opinion: holy war and pacifism.

Firstly, some people use Christianity as justification for religious propagation by conquest, with the often-quoted example of the Crusades between 11th and 17th Centuries. However, I would suggest that kingdom-by-conquest runs contradictory to Christian theology. Peace is repeatedly described as one of the fundamental and defining attributes of the gospel (“the gospel of peace”(1), “He [Jesus] came and preached peace”(2)), Jesus Christ (the “prince of peace”(3)), righteousness (“peacemakers who sow in peace reap a harvest of righteousness”(4)), and eternal life (“nation will not take up sword against nation, nor will they train for war anymore.”(5)). Violence and warfare are in direct conflict with the very character of Jesus and the gospel.

At this point some would legitimately raise the objection of the God-sanctioned violence of the Old Testament, particularly the slaughter of the Canaanites in the book of Joshua. Violence in the bible is a complex and difficult issue, that warrants a blog of its own. However, in summation, the violence of the Old Testament is not written as an example for Christians to follow. Rather, in the book of Joshua, God uses Israel as his unique vehicle of judgement on the sins of the Canaanites. As God declares to Israel prior to the invasion of Canaan: “it is on account of the wickedness of these nations that the Lord is going to drive them out before you.”(6) The wars in Joshua are there, not as exemplars of religious crusades, but as demonstrations of God’s judgement and the seriousness of sin.

However, despite being named “The Prince of Peace”, I do not think Jesus advocated pacifism either. In the book of Ecclesiastes, we read:

“There is a time for everything, and a season for every activity under the heavens… a time to love and a time to hate, a time for war and a time for peace”.

In Luke 3:14, following a sermon by John the Baptist about the imminent coming of Jesus, we read:

Then some soldiers asked him [John the Baptist], “And what should we do?” He replied, “Don’t extort money and don’t accuse people falsely—be content with your pay.”

Following Jesus is clearly not incompatible with being a soldier- otherwise John the Baptist would have sent the newly-converted soldiers to the Job Centre. Rather, John the Baptist sees warfare as having a legitimate role in our fallen world, but one which is transformed by knowing and following Jesus.

And so, I do not think Christianity backs either holy war or pacifism. Rather, I believe Christianity advocates the idea of “Just War”.

Just War

“Just War” was a term coined by the 4th Century church father St Augustine of Hippo, and codified and popularised 900 years later by St Thomas Aquinas. Aquinas laid out the following criteria that have to be met to justify going to war:

  1. Just Authority

  2. Just Cause

  3. Just Intention (/Limitation)

  4. Last Resort

I think these principles are biblical and helpful in discerning the ethics of modern warfare. For the remainder this article, I shall be unpacking these four principles, explaining their biblical roots, applying them to the challenges of modern warfare, and then finally applying them to the USA-Iran tensions.

1. Just Authority

This states that war must only be sanctioned by a legitimately instituted authority. This is biblical, 1 Peter 2:13-14 reads: “Submit yourselves for the Lord’s sake to every human authority: whether to the emperor, as the supreme authority, or to governors, who are sent by him to punish those who do wrong and to commend those who do right.” This does not justify or endorse tyrannical, dictatorial or otherwise abusive national leadership. However, verses like this show us that “government” is a God-established system of societal order that should be upheld.

This has several implications for modern warfare. Firstly, it deters involvement in militia warfare, as well as engagement in lone-wolf attacks. Secondly, I believe it maintains the notion of the default obedience of soldiers to their commanders, with conscientious objection in only exceptional circumstances. And thirdly, it gives us a strong moral mandate to obey international laws.

This third point is worth unpacking in the context of the USA-Iran tensions. In the UK parliament on Wednesday 8th January, Prime Minister Boris Johnson and Opposition Leader Jeremy Corbyn clashed over whether the US drone attack on Soleimani was legal or not. The legality of the strike hinges on whether there was sufficient evidence of an imminent threat to the USA posed by Soleimani, that warranted the military intervention undertaken. Obviously, I am in no position to say one way or the other, for the purported evidence is yet to be made public. But it is a question that the international community must raise.

It also goes without saying that threatening international war crimes over Twitter seems to fly in the face of the principle Just Authority.

2. Just Cause

This principle states that war is only just if it is done for a morally just and good cause, such as self-defence, defence of another, or the restoration of a good that was previously denied, rather than for selfish or sinful motives, such as vengeance, ideological displeasure, or an exertion of power. Again, this is biblically rooted; in Micah 6:8, God commands the Israelites “He has shown you, O mortal, what is good. And what does the Lord require of you? To act justly and to love mercy and to walk humbly with your God.”

It is this principle that often fuels political debates around the justification of specific military interventions. Is a war simply an ideologically-driven exertion of power? Or is there morally justifiable reason for intervention? Clearly these discussions are complex and situation-specific. I think most would agree that the RAF were justified in taking to the skies during the Battle of Britain. I think many people would agree that there was just cause for the US Navy Seals’ assignation of Osama bin Laden in 2011. But was there just cause for the UK to intervene in the Falklands? Or in Afghanistan? Or Iraq?

And was there just cause in President Trump ordering the killing of General Soleimani? Was there just cause in Iran retaliating by attacking US-occupied air bases? Who stood to benefit from these attacks? And was a significant moral good served? I do not think we have enough information at this stage to answer these questions, and knee-jerk praise or condemnation is unlikely to be helpful in this circumstance. Rather, sober, thought-through, prayerful consideration is surely warranted.

3. Just Intention

I prefer to call this “Just Limitation”, for this principle sets limits to the extent of war. For a war to be just, it must be:

  • Discriminate- limited only to the legitimate and necessary targets of war

  • Proportionate- limited to just and pre-defined causes

  • Responsible- limited by the good of the war outweighing and thus justifying the damage

This principle finds its roots in the general principle that the bible never holds war up as an ideal, but rather as a sometimes-necessary burden that humans need to bear whilst living in a sin-stained, fallen world. And thus warfare must be limited strictly to what is necessary for good to flourish.

The discriminatory and responsibility elements of Just Intention cast concern over the ethics of both biological and nuclear weapons, for which the consequential damage is very difficult to limit or predict. I am not necessarily advocating for unilateral nuclear disarmament, for I believe nuclear deterrents may well be a proportionate and responsible possession in some circumstances. But actual engagement in biological or nuclear warfare would be a whole different issue.

One of the slightly reassuring aspects of the USA-Iran tension is that some restraint appears to have been taken by Iran as they launched missiles at the US-occupied airbases, without causing confirmed fatalities. And at time of writing (10th January) there appears to be restraint being exercised by both sides as the military threats appear to be de-escalating (for now).

Another relevant discussion is over Iran’s nuclear capabilities, following the USA’s withdrawal from the Iran Nuclear Deal in May 2018. Whether Trump's actions, both in 2018 and now, are making it more or less likely that Iran will develop nuclear military capability, is clearly a matter being debated at the highest levels of politics and diplomacy. But I think the topic of nuclear weapons needs to always be in mind whilst decisions are being made on military intervention in Iran, for the ethical implications may be grave.

4. Last Resort

The final core principle of Just War to unpack is that war should be the last resort option, when all other paths have been assessed and ruled out. Jesus preached a message of radical, world-changing, perplexing love and kindness in affliction. He commands in the Sermon on the Mount: “love your enemies and pray for those who persecute you”(8). Warfare should thus be the final and deeply painful last resort when radical generosity, compassion, forgiveness and love still leave just causes unfulfilled.

In the modern context, it follows that parliaments and leaders should pursue peaceful diplomatic and political resolutions to international conflicts in all possible circumstances. Of course, there are situations where rapid and immediate military decisions are necessary. But in the main, I think a slowness to war in order to allow the exploration of peaceful options has to desirable.

One of the most chilling parts of the USA-Iran episode thus far has been the New York Times-reported allegation that Trump’s advisers presented him with a list of options regarding Iran, wrongly thinking that he would not choose the “most extreme” option of killing Soleimani (9). I think we are wise to not automatically believe everything reported in the media. However, we must ask: did the USA really see military intervention in Iran as the last resort option?

Modern Warfare: When Is Intervention Moral?

The situation between USA and Iran is evolving day by day, and I certainly do not have enough information at present to form any firm conclusions about the morality of the countries’ actions. Was Soleimani a genuine imminent threat to US civilians? Was the killing of Soleimani a legitimately legal and necessary last resort? Was Iran justified and proportionate in their retaliatory missile strikes? What does the future hold for the region and the world?

As we wrestle with the challenging and evolving ethical questions raised by modern warfare, I think the principles of Just War, which are rooted firmly in the wisdom of the bible, provide us with a relevant and important framework on which to build ethical views. War can only be just if sanctioned by a legitimate authority, driven by a morally just cause, limited in its scope and predictable damage, and a genuine last resort when peaceful resolutions have been exhausted.

Let me end with the words of theologian John Stott from his book Issues Facing Christians Today, in which he dedicates a chapter to the ethics of modern warfare:

“Every Christian is called to be a peacemaker… True, we shall not succeed in establishing Utopia on earth, nor will Christ’s kingdom of righteousness and peace become universal within history. Not until he returns will swords be beaten into ploughshares and spears into pruning hooks… [But] does Christ’s prediction of famine inhibit us from seeking a more equitable distribution of food? No more can his prediction of wars inhibit our pursuit of peace. God is peacemaker. Jesus Christ is peacemaker. So, if we want to be God’s children and Christ’s disciples, we must be peacemakers too.”(10)

  1. Ephesians 6:15

  2. Ephesians 2:17

  3. Isaiah 9:6

  4. James 3:18

  5. Isaiah 2:4

  6. Deuteronomy 9:4b

  7. Ecclesiastes 3:1-8

  8. Matthew 5:44


  10. John Stott, Issues Facing Christians Today, 4th ed, p. 131


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