Will Russia Attack Ukraine?
In line with many observers, we do not expect Russia to invade Ukraine. However, we cannot completely rule out some form of military action by Russia, if the tense situation between Ukrainians and ethnic Russians deteriorates sharply.
If we were to see Russian military intervention, it would most probably be limited to Crimea, in the south of Ukraine, where sympathies for Russia are strongest. This peninsula has the highest proportion of ethnic Russians (almost 60% of the local population) in Ukraine, and it already has a Russian military presence in the form of a major naval base in the city of Sevastopol.
If tensions between pro-Kiev and pro-Moscow groups result in more violence, the Kremlin could decide that protecting ethnic Russians warrants sending more troops to the region. The Black Sea Fleet naval base would theoretically allow Russia to increase its military personnel on the Crimean peninsula without explicitly invading the sovereign territory of Ukraine.
Russia could then choose to move personnel deeper into Crimea if invited to do so by regional officials. At the time of writing, the situation in Sevastopol looks highly fluid, with pro-Moscow demonstrators naming a Russian citizen, Alexei Chalov, as the mayor of Sevastopol, and with a group of around fifty heavily armed men having occupied the parliament building.
Tensions between pro-Kiev and pro-Moscow groups might easily escalate in the next few days.
An increase in Russian military personnel at Sevastopol alone may not prompt a military response from either Ukraine or Western powers.
However, the really big question is what would happen if Russia carried out a direct land invasion of Ukrainian sovereign territory. We still regard this as unlikely, given that Ukraine is a vast country with a large military. In other words, the costs to Russia would be high. But, supposing it happened, what then?
Ukraine is not a member of NATO, so in theory the West would not be obliged to intervene. That said, could the US and European powers stand by and accept such a blatantly aggressive move by Russia? They did in Georgia in 2008, when Russia briefly invaded the South Caucasian state to support the separatist regions of South Ossetia and Abkhazia, which Moscow subsequently recognised as independent.
Also noteworthy is that the US and its allies have very little appetite for military campaigns, as evidenced by their reluctance to act against Syria. Indeed, although the US has withdrawn from Iraq, and the NATO troop presence in Afghanistan is well below its peak, Western countries are probably more militarily exhausted now than they were in 2008, thanks to five more years of combat in Afghanistan, and because of the longer than expected duration of the air campaign in Libya in 2011.
On the one hand, doing nothing to defend Ukraine might leave a very bitter taste in the mouths of the West, along the lines of the Soviet invasions of Hungary in 1956 and Czechoslovakia in 1968. On the other hand, a NATO military response could result in a major new war in Europe. Such a war would not necessarily become a 'world war' – after all, the US and USSR engaged in direct confrontation in the skies above Korea during the Korean War (1950-1953). But there would at the very least be a high risk of a new Cold War.