Russia's current military position in Ukraine is very exposed and has come at a great cost relative to its limited political gains. The strategic bastion of Crimea is defensible as an island but is subject to potential isolation. The position of Ukrainian separatists and their Russian backers in eastern Ukraine is essentially a large bulge that will require heavy military investment to secure, and it has not necessarily helped Moscow achieve its larger imperative of creating defensible borders. This raises the question of whether Russia will take further military action to secure its interests in Ukraine.
To answer this question, Stratfor examined six basic military options that Russia might consider in addressing its security concerns in Ukraine, ranging from small harassment operations to an all-out invasion of eastern Ukraine up to the Dnieper River. We then assessed the likely time and forces required to conduct these operations in order to determine the overall effort and costs required, and the Russian military's ability to execute each operation. In order to get a baseline assessment for operations under current conditions, we initially assumed in looking at these scenarios that the only opponent would be Ukrainian forces already involved in the conflict.
One of the most discussed options is a Russian drive along Ukraine's southern coast in order to link up Crimea with separatist positions in eastern Ukraine. For this scenario, we assumed that planners would make the front broad enough to secure Crimea's primary water supply, sourced from the Dnieper, and that the defensive lines would be anchored as much as possible on the river, the only defensible terrain feature in the region. This would in effect create a land bridge to secure supply lines into Crimea and prevent any future isolation of the peninsula. Russia would have to drive more than 400 kilometers (250 miles) into an area encompassing 46,620 square kilometers, establish more than 450 kilometers of new defensive lines, and subdue a population of 2 million.
Taking this territory against the current opposition in Ukraine would require a force of around 24,000-36,000 personnel over six to 14 days. For defensive purposes, Russian planners would have to recognize the risk of NATO coming to Kiev's assistance. Were that to happen, Russia would have to expand the defensive force to 40,000-55,000 troops to hold the territory.
Planners must also consider the force needed to deal with a potential insurgency from the population, which becomes decidedly less pro-Russia outside of the Donbas territories. Counterinsurgency force structure size is generally based on the size of the population and level of resistance expected. This naturally leads to a much wider variance in estimates. In this scenario, a compliant populace would require a force of only around 4,200 troops, while an extreme insurgency could spike that number to 42,000. In this particular case, no extreme insurgency is expected, as it would be in cities such as Dnepropetrovsk, Kharkiv or Kiev. The defensive force could overlap with the counterinsurgency force to some degree if there were no external threat, but if such a threat existed the forces would have to be separate, potentially doubling the manpower required to secure the territory.
These first two scenarios have a serious flaw in that they involve extremely exposed positions. Extended positions over relatively flat terrain — bisected by a river in one scenario — are costly to hold, if they can be defended at all against a concerted attack by a modern military force. Supply lines would also be very long throughout the area and, in the scenario that extends beyond the Dnieper River, rely on bridging operations across a major river.
A third scenario would involve Russia taking all of eastern Ukraine up to the Dnieper and using the river as a defensive front line. When it comes to defending the captured territory, this scenario makes the most sense. The Dnieper is very wide in most places, with few crossings and few sites suitable for tactical bridging operations, meaning defending forces can focus on certain chokepoints. This is the most sensible option for Russia if it wants to take military action and prepare a defensive position anchored on solid terrain.
However, this operation would be a massive military undertaking. The force required to seize this area — approximately 222,740 square kilometers — and defeat the opposition there would need to number 91,000-135,000 troops and advance as much as 402 kilometers. Since the river could bolster defensive capabilities, the defensive force could remain roughly the same size as the attacking force. However, with a population of 13 million in the area, the additional troops that might be required for the counterinsurgency force could range from 28,000-260,000. Russia has approximately 280,000 ground troops, meaning that the initial drive would tie down a substantial part of the Russian military and that an intense insurgency could threaten Russia's ability to occupy the area even if it deployed all of its ground forces within Ukraine.
One positive aspect would be that this operation would take only 11-14 days to execute, even though it involves seizing a large area, because Russia could advance along multiple routes. On the other hand, the operation would require such a vast mobilization effort and retasking of Russian security forces that Moscow's intent would be detectable and would alarm Europe and the United States early on.
Two remaining options that we examined were variations on previous themes in an effort to see if Russia could launch more limited operations, using fewer resources, to address similar security imperatives. For example, we considered Russia taking only the southern half of eastern Ukraine in an effort to use decidedly less combat power, but this left the Russians with an exposed flank and removed the security of the Dnieper. Similarly, a small expansion of current separatist lines to the north to incorporate the remainder of the Donetsk and Luhansk regions to make the territory more self-sustaining was considered. Both operations are quite executable but gain little in the grand scheme.
The final scenario we considered was the most limited. It involved Russia conducting small temporary incursions along the entirety of its border with Ukraine in an effort to threaten various key objectives in the region and thus spread Ukraine's combat power as thin as possible. This would be efficient and effective for the Russian military in terms of the effort required. It could accomplish some small political and security objectives, such as drawing Ukrainian forces away from the current line of contact, generally distracting Kiev, or increasing the sense of emergency there, making the Ukrainians believe Russia would launch a full invasion if Kiev did not comply.
For all of the scenarios considered, the findings were consistent: All are technically possible for the Russian military, but all have serious drawbacks.
Not one of these options can meet security or political objectives through limited or reasonable means. This conclusion does not preclude these scenarios for Russian decision makers, but it does illuminate the broader cost-benefit analysis leaders undertake when weighing future actions. No theoretical modeling can accurately predict the outcome of a war, but it can give leaders an idea of what action to take or whether to take action at all.