Demonstrations in eastern Ukraine over the weekend raised the stakes in the country's ongoing political crisis and could signify upcoming action in terms of Russia's position in the country. Pro-Russian protesters stormed regional administration buildings in the eastern Ukrainian cities of Donetsk, Kharkiv and Luhansk on April 6. As of April 7, the buildings remained occupied by demonstrators, some of whom were armed. Although a Russian military intervention in eastern Ukraine remains unlikely, Moscow could support an informal security presence in these regions in order to advance its political goals in Ukraine. 

Protests have been occurring sporadically in eastern Ukraine ever since the uprising against former President Viktor Yanukovich and the installation of a Western-oriented government in Kiev. Eastern and southern Ukraine are much more oriented toward Russia than the western and central parts of the country, and pro-Russian and anti-government protests have occurred regularly in several eastern cities — including Donetsk, Luhansk and Kharkiv — since Yanukovich's ouster in February.

The protests over the weekend were similar to previous demonstrations. However, a key difference in the most recent rallies was the presence of armed men, reportedly carrying AK-74s in Donetsk and Luhansk and handguns in Kharkiv. These men appeared to have training and experience in handling such weapons, and their presence enabled a small number of demonstrators to continue occupying some of the administration buildings into April 7. Meanwhile, protesters in Donetsk have called for a referendum on the region's independence for May 11 and have asked Russia to deploy a peacekeeping force to protect the voting process.

In reaction to these events, Ukrainian Prime Minister Arseniy Yatsenyuk said that a "plan to destabilize the situation is being put in place" in eastern Ukraine, a veiled reference to Russian involvement. However, Ukrainian security forces have not tried to confront the demonstrators, knowing that this could provoke a Russian intervention. Instead, authorities from Kiev, including Ukrainian First Deputy Prime Minister Vitaliy Yarema and acting Interior Minister Arsen Avakov have been dispatched to Donetsk and Kharkiv respectively to try to resolve the situation. Media reports and pictures on Twitter indicate that some roads into the east have been blocked in an effort to cut off the separatists from supply lines rather than confront them directly. 

It is unclear whether this will be enough to offset the demonstrations or undermine the position of the pro-Russian protesters. The degree to which these demonstrations are being driven or coordinated from within Russia is also unclear. However, U.S. officials have said that Russia may have instigated these protests, and an intercepted radio communication from alleged protest organizers has suggested that the demonstrations in Donetsk, Luhansk and Kharkiv were coordinated from "the same center." Also, Russia clearly demonstrated in Crimea its ability to organize or at the very least co-opt demonstrations to meet its political objectives. Moreover, the protests in the east have notable similarities to the developments in Crimea — particularly the use of plainclothes armed men to secure key infrastructure and a subsequent call for a referendum and Russian military protection.

Still, these events do not necessarily mean a formal Russian military intervention in eastern Ukraine is forthcoming. Stratfor has outlined the tremendous possible costs of such an operation, particularly the logistical needs for a full-scale invasion. Also, the Ukrainian military would be in a far better position to challenge Russia in mainland Ukraine as opposed to Crimea, where Russian units were already stationed. Moreover, popular support for Russian action is far lower in eastern Ukraine than in the ethnic Russian-majority Crimea, and any Russian actions would likely face strong opposition there, possibly sparking irregular or guerrilla warfare. Russia also does not want to elicit a meaningful response from the United States and NATO.

These conditions make the presence of plainclothes armed men in the latest protests that much more important. Rather than spurring Russia to formally intervene militarily on their behalf in less than ideal conditions, these men could lay the groundwork for the growth of an irregular armed force in eastern Ukraine that resists authorities in Kiev. Indeed, the demonstrations against Yanukovich in Kiev set a dangerous precedent for this outcome by involving armed rebel groups to force political change. The pro-Russian protesters seem to be using the same tactics on the same dubious legal grounds.

This could give Russia enormous leverage in shaping Ukraine's political evolution. Moscow has insisted all along that the current government in Kiev is illegitimate, given the way it was formed, and that any government should take the interests of the eastern regions into account — particularly when it comes to making significant moves toward EU integration. If the government continues to resist Russia on this issue, Moscow could respond by bolstering this kind of irregular force rather than involving Russian forces in an intervention.

The incidents in the east, including the calls for referendums, also put the timeline for Ukraine's presidential election — scheduled for May 25 — in question. Moreover, if Russia can conceal its hand, it will be difficult for the Europeans to respond directly to such developments. After all, how do you impose sanctions on suspected Russian covert backing for armed groups, and who would want to lead that investigation?

Therefore, supporting such groups — along with applying severe economic pressure on Kiev — could allow Russia to undermine Ukraine's elections and Kiev's attempts to integrate with the European Union. This strategy would also be difficult for the West to counter, because it involves tactics used in the Western-backed protests in the final stages of the uprising against Yanukovich. This strategy could make the West and the Ukrainian government more willing to negotiate, lest they risk increasing complications with Moscow and pro-Russian forces in eastern Ukraine.