Western diplomatic efforts over Russia's annexation of Crimea can impact the most unlikely areas, as Justin Timberlake and Miley Cyrus found out a few days ago when forthcoming gigs at the Hartwall Arena in Helsinki were put at risk because the venue is owned by three Russian businessmen who have been prohibited by the US from undertaking any financial transaction with US citizens or companies.

Unless special dispensation is granted by the US treasury, no American can play at Hartwall Arena until Russian forces leave Crimea.  In the end, the gigs are going ahead.  "The sanctions will not have an impact on Hartwall Arena nor our business there," Nina Castren, the chief executive of Live Nation Finland said.

Pop concerts aside, the question for us is, are diplomatic efforts enough, and if the West chooses to go to war over the question of the Crimea or any further Russian ventures into Ukraine, will it be right to do so?

To help answer that question, Christian Today spoke three leading scholars of the Christian 'just war' tradition and whether it applies in this context.

Robert J Delahunty is a law professor at the University of St Thomas School of Law and co-author of the paper 'From Just War to False Peace' published in the Chicago Journal of International Law.

Brian Orend is the Director of International Studies and a professor of Philosophy at the University of Waterloo in Waterloo, Ontario.

Gregory M Reichberg is the head of the Olso based Peace Research Institute and co-editor of the text "The Ethics of War: Classic and Contemporary Readings"

Christian Today: Do you believe that an intervention by Western forces to return the Crimea to Ukraine could be regarded as a just war?

GR: No, this would not be a just military action on the part of the Western forces.

Russia may have a legitimate claim on Crimea, only by a fairly recent historical accident – Khrushchev's "gift" – gave Crimea to Ukraine; the vast majority of citizens living there are ethnic Russians; and Russia has its major Black sea naval base in Crimea, which it perceived to be threatened by political developments in Ukraine.

However Russia pressed its claim in the wrong way. Instead of invading Ukraine, they should have negotiated. By invading Crimea and pressing for a referendum under these circumstances, Russia violated international law.

This violation would provide insufficient just cause for a military reaction on the part of Western powers. On prudential grounds, such a reaction would be disproportionate, with little hope of success.

Since Russia broke an important norm of the international community when it resorted to force rather than negotiating over its claim, there is a basis for applying economic sanctions against Russia, but no necessity for using armed force in this instance, since it is not a last resort.

RD: Just wars have four main elements. The party going to war must (1) act under rightful authority, (2) have a proper intention, and (3) possess a just cause. Also, some just war theorists include (4) proportionality i.e. that the good outcomes of the war outweigh the likely harm the war will cause.

1) The first test ("rightful authority") distinguishes public wars from private violence like feuds or vendettas. A Western intervention would be authorised by sovereign governments, so this test would appear to be satisfied.

2) The second test ("proper intention") also appears to be satisfied. A Western intervention's purpose would be to restore Ukraine's sovereignty over Crimea.

Before the Russian invasion, conquest and annexation of the Crimea, Ukraine was the internationally recognized sovereign over that territory, even Russia did not contest that.

The West would have less creditable purposes for intervening, such as extend its sphere of influence further eastward, or thwarting Russia's emerging challenge to its aim of retaining global leadership.

However, given the West's extreme reluctance (so far) to take or even to contemplate military actions against Russia provides strong evidence that these are not its objectives.

3) Restoring territory wrongfully taken to its rightful owner is a perfectly classic example of "just cause". But for this to be a just war, the West would have to limit itself to only liberating Crimea.

Destruction of Russian military power, occupation of Russian territory or destruction of the Russian economy beyond what was necessary to recover the Crimea would bring doubts over the justice of the Western "cause".

4) Proportionality is a requirement for a just war in international law, and here is where we see a Western intervention in Crimea probably not being just.

Forcible removing Russian forces from the Crimea would accomplish some good - restoration of Ukrainian sovereignty, and discouragement of future aggression by Russia or other powers.

But intervention carries enormous risks of a larger conflict between Russia and the West. Armed conflict would probably not be confined to the Crimea. The Putin government would likely believe that its survival was at stake if it lost the Crimea, and so would throw all the resources available to it into the conflict.

A Russian invasion of eastern (or even western) Ukraine would seem very likely. Russia could well seize the occasion to invade other neighbouring states that were once part of the Soviet Union or Russian Empire, including Moldova, the Baltic States, or Finland.

We should also not neglect economic issues. The West has not recuperated fully from the financial crisis of 2008. A war – even a short and successful one – could wreck the recovery.

The West might also find itself paying for post war reconstructions. Given the extensive harm that would likely ensue even from a "conventional" war over the Crimea, it would seem that the "proportionality" condition would not be met.

CT: Can Russia defend its actions in the Crimea using the just war tradition?

BO: The claims here are murky. The Russians would say that Crimea has this Russian majority, who want to be with Russia, and they ran this referendum to show the West this.

Plus, there's this huge Russian naval base which has been there for ages, and the whole issue of how Ukraine used to be part of the Soviet Union for a long time, and used to be run by Russia. Thus, there's a contestedness about who "owns" the Crimea.

Borders only have clear moral importance when they establish the limits of a clear and separate political community. If they don't - if they are deeply contested - then we have reduced grounds for viewing them as being sacred or inviolable.

If re-drawing the borders helps keep the peace, then that doesn't have to be irrational, or cowardly capitulation. Here, it may allow western/central Ukraine to pursue the deeper ties to the West (EU) that it wants, whereas the Crimea and perhaps the East are allowed to retain the traditional links to Russia.

RD: If Russia's actions had been limited to protecting the lives and safety of ethnic Russians living in the Crimea from the (alleged) dangers to which they were exposed by the collapse of the pro-Russian Ukrainian government, the case for Russian intervention would have been stronger.

In his speech of March 18, President Putin emphasised this purpose, claiming that "those who opposed the coup [against deposed Ukrainian president Viktor Yanukovych] were immediately threatened with repression. Naturally, the first in line here was Crimea, the Russian-speaking Crimea. In view of this, the residents of Crimea and Sevastopol turned to Russia for help in defending their rights and lives."

However, by annexing the Crimea, Russia went well beyond such limited and temporary action. In other words, annexation was disproportionate.

CT: If Russia had more territorial ambitions, (such as has been rumoured with Finland) would that change the just nature of any potential war?

RD: The question can be understood in two distinct ways.

If the question is whether a war to defend those countries against a Russian invasion would be just, the answer is 'yes'.

Russia has no valid claim whatsoever to Finland, Moldova, the Baltic States or (at least the western half of) Ukraine. If those nations resisted Russian invasion by force, they would be acting in justified self-defence. If the West assisted them militarily, it would be acting justly.

The question might also be interpreted to be: would Western intervention in the Crimea be just if it is true that Russia has territorial ambitions it has not yet acted upon against Finland or other nations.

While that supposition about Russia's longer-range intentions would affect the proportionality analysis outlined above, I do not think it would alter the outcome of that analysis. In other words, it would not justify Western intervention in the Crimea.

BO: With Finland you are talking about a settled political community, with very few ethnic Russians living there. The border means much more, and thus an armoured crossing of it by the Russians would be much more clearly objectionable.

I'd be very surprised if Putin decided to go that route - he's more likely to go after eastern Ukraine, I'd think - but, I suppose one never knows. So, in the case of something like Finland, the West's case in terms of just cause would be impeccable - resisting an aggressive invasion across a settled border - but, I fear, the issues of consequences and probability of success would still arise, and sharply.

CT: Does the fact that the UK, France, the US, and Russia are all nuclear powers alter the just war question?

GR: Yes, it can affect the proportionality calculation. Any direct confrontation between states possessing nuclear weapons carries the risk that such weapons will be used. The side-effect harm would be massive.

From another perspective the nuclear question can affect our assessment of whether or not Russia had a just cause to annex Crimea. Ukraine's agreement to divest itself of its Soviet nuclear weapons was conditional upon its territorial integrity being respected by nuclear states.

Now countries that are developing or already have nuclear weapons can see the downside of disarming. Would Russia have invaded Crimea if Ukraine still had nuclear weapons?

A strong reaction, even if not military, is justified also because of the danger that Russia might seize further territory where numerous Russians live (Eastern Ukraine and Transnistria). It needs to be put on notice that such action is unacceptable and that serious consequences will result.

CT: If Ukraine had been a member of NATO would that change whether the war would be just for the West to fight?

RD: Yes. In that circumstance, even the proportionality condition would be likely to be met. The peace of Europe (and of the world) depends to a very considerable extent on the credibility and vitality of NATO.

If NATO were to stand by as a Member State was invaded and its territory wrongfully seized, the alliance would be shattered. That in turn would magnify the risk of further Russian encroachments in Europe; indeed, it could raise the chances for future conflict between (say) Greece and Turkey or even Germany and Poland.

CT: In your opinion, what is the most important question to ask when considering whether a conflict can be just?

RD: Really, all of the questions posed by the just war theory are essential. But decision-makers should concentrate on the question, what will the post-war consequences be? Studies show that wars often begin in a state of extreme over-confidence: both leaders and peoples are prone to believe that the war will be short and victory swift. That belief is routinely disappointed.

Further, the recent experience of the Second Gulf War shows that even when a military "victory" is achieved, it may be merely the prelude to further, prolonged conflict (the Iraqi insurgency). "Victory" may also leave the "victor" with the intractable tasks involved in a post-war reconstruction of the enemy's society, economy and polity.

Finally, the political leadership should also reckon with the consequences of war for its own people, including, not least, its soldiery. David Finkel's 2011 book 'Thank You For Your Service' graphically demonstrates the horrifying effects of combat on the lives of wounded American veterans of recent wars in Iraq and Afghanistan.

Their injuries were not only physical, but often mental and even moral. The justification must be substantial before a government can ask such sacrifice from those who fight its wars, and from their families.