What Would Russian Troops Do Once They Cross the Ukrainian Border?

If Russia decides to invade eastern Ukraine, extending its grip on its neighbor’s territory from the Crimean peninsula to its eastern and southern provinces, how would it do so?

Since Russia invaded and annexed Crimea, the prospect of a full-fledged Russian invasion has gained new currency with Ukraine’s government locked in a bitter stand-off with separatists in the country’s east. Pro-Russian activists and gunmen have seized government buildings there, and while the government in Kiev has pledged to oust them, that ultimatum has so far gone unenforced.

Many observers speculate that the seizure of government buildings have come at the behest of Moscow — senior U.S. officials have claimed as much — in order to stir up a pretext for invasion. Once Moscow’s agents have sowed sufficient chaos, the thinking goes, Russian forces will swoop in from their positions just outside Ukraine’s borders and restore the peace, selling their invasion as a peacekeeping mission.

But what will Russian forces do once they cross the Ukrainian border? In a little-noticed and increasingly prescient report from earlier this month, analysts at the Royal United Services Institute, a defense think tank, lay out a series of scenarios spelling out possible courses of actions for Russian troops invading the eastern and southern provinces of Ukraine.

While a Russian invasion of Ukraine is far from certain, recent events in Ukraine mirror events in the lead up to the stealth invasion of Crimea. And even if predictions of a Russian invasion do not come true, these scenarios provide a framework for considering Moscow’s military options.

According the authors of the report — Igor Sutyagin, a research fellow at RUSI, and Michael Clarke, the institute’s director general — Russia has some 50,000 troops lined up against roughly 70,000 Ukrainian troops. While Ukraine possesses a numerical advantage in troops, Kiev’s forces are “poorly equipped and would struggle to mobilise fully.” “In the event of a military clash,” the report notes, “its formations would be locally outnumbered and certainly outgunned by Russian forces and their reserves.”

The map below presents a rough guide to the location of Russian troops massed along Ukraine’s borders. As the report notes, the Polessya Group and Northern Group are poised to strike quickly at Kiev. While reports on Monday indicate that Ukrainian commanders have shifted their forces east to crack down on separatists in the east, Russian forces along the northern border prevent them from moving east in greater numbers. Moreover, as seen further below on the map tracking Ukrainian troops deployments from early this month, its forces are already heavily clustered in the west.

Under the first scenario laid out by the report, Russian troops have been placed in large numbers along Ukraine’s border in order to force Kiev and the West to acquiesce to Moscow’s land gains in Crimea. According to this line of thinking, Russian troops won’t cross the border and “would be stood down quite quickly once the political process has given Putin the recognition of his fait accompli over the Crimea.” Recent unrest in Ukraine points to the unlikelihood of this scenario. Moreover, the report’s authors consider this scenario less probable given the placement of Ministry of Interior troops on high alert, whose purpose is typically to pacify local populations.

Under a more aggressive scenario, “Russian forces would covertly support, or even engineer, civil unrest throughout south-east Ukraine and use that as a pretext for opening the secure land corridor to Crimea through Donetsk, Zaporizhia, and Kherson oblasts.” As shown on the map above, the Donbass Group and troops stationed in Crimea would likely move to secure that territory.

Under the third scenario, “unrest and separatist pressures in south and eastern Ukraine, real or manufactured, may present a dangerous, but nevertheless tempting opportunity to split the country in two, south and east of the Dnieper River.” As the map indicates, Russian forces are well-positioned to execute such a split.

But Russia could go even further than that and carve out a “western corridor from Transnistria in Moldova into Crimea through Odessa and Mykolaiv Oblasts, which would encompass the historic city of Odessa itself.” Such a move would create a southern arc of Russian territory in Ukraine, uniting the pro-Russian breakaway region of Transnistria with newly claimed Russian lands. (As my colleague Christian Caryl reports from Odessa, residents of that city aren’t exactly enthused at the prospect of incorporation into Russia.)

So how are Ukrainian troops poised to respond to these threats? In short, not well. Recent reports have Ukrainian troops moving east, but it is unclear whether they are redeploying in large numbers. And even if they effectively shift ahead of a Russian military incursion, they would likely be outmatched by their opponents.

For all this prognosticating, it remains highly unclear which of these scenarios is most likely to play out. For now, we remain somewhere between scenarios one and two, with Russian troops holding along the eastern borders to secure their land gains in Crimea and Russian agents stirring up trouble in the east as a potential justification for a future invasion.

Several geopolitical factors, the authors argue, make some of these scenarios more likely than others. As the report notes, Russia would greatly ease Crimea’s isolation by securing a land corridor between Russian territory and the peninsula. Moreover, by securing a land corridor to Crimea, Russia would end a dispute over the Kerch Strait and secure exclusive access for Gazprom to energy deposits in the Sea of Azov. Moreover, key elements of the Russian defense industry — including its missile programs — rely on Ukrainian suppliers in the country’s east. Its SS-18 intercontinental ballistic missiles, for example, are designed and manufactured in Dnepropetrovsk on the Dnieper River.

But whether that indicates Russia will pursue the most aggressive options available to it, is far from certain.”It could be argued that since most of the military plants in question are in south and east Ukraine, the temptation to follow the third and fourth scenarios will be all the greater,” the report says. “To suggest these scenarios for the sake of capturing the production at these various plants would be a very nineteenth-century way of looking at a twenty-first century relationship. However, even that cannot be ruled out in current circumstances.”