On Dec. 9, following a burst of diplomatic activity including a phone conversation between Russian President Vladimir Putin and Ukrainian President Petro Poroshenko, German mediation and French President Francois Hollande's unannounced visit to Moscow, hostilities decreased notably along the contact line in eastern Ukraine. A cease-fire has been nominally in place in eastern Ukraine since Sept. 5. However, efforts to make the cease-fire more effective, including the withdrawal of some heavy equipment and an increase in the number of prisoner exchanges, contributed to a significant decrease in cease-fire violations — especially Grad and artillery fire — after Dec. 9.
As the continuing discussions have failed to make significant progress, even during a meeting of Ukrainian, Russian and Organization for Security and Cooperation in Europe representatives in Minsk on Dec. 24, the number of cease-fire violations has escalated. Over the past few weeks, the fighting has returned to levels seen before Dec. 9. Grad and artillery systems have reappeared, and intense artillery bombardments have resumed along the entire contact line. However, this escalation is still largely within the parameters set in the Sept. 5 cease-fire, and neither side has launched actual ground offensives meant to recapture significant territory.

Some of the most intense fighting during this re-escalation has occurred at the Donetsk airport. The airport initially drew the separatists' focus because of its importance to Ukrainian logistics, but over time it has become more of a symbolic target because of the ongoing entrenched fighting there. Both sides have committed many resources to holding the airport or trying to take it, and it has become difficult for either side to disengage. Moreover, because both sides are close to each other in an urban environment, cease-fire violations are more frequent and carry a greater risk of escalation.
Separatists have fought their way into the main terminal, where Ukrainian forces continue to defend their positions. As the fighting continues, both sides claim to hold the main terminal. With events at the airport still unfolding, localized escalations could occur and could even extend beyond the established parameters of the cease-fire, both at the airport and at other key contested sites, such as the town of Debaltseve. However, the higher-level political and financial constraints on Kiev and Moscow will motivate both sides to try to contain significant escalations and prevent them from affecting the broader status of the cease-fire. In the larger picture, the conquest of the airport terminal still does not represent a meaningful change in the military balance or in eastern Ukraine's threat to Kiev.
What the Fighting Signals About Negotiations
The recent uptick in violence indicates that Russia currently does not have a strong incentive to significantly reduce hostilities along the contact line. For Russia, fighting along the contact line in eastern Ukraine is a lever in its complex negotiations with Ukraine.
The talks are key for allowing Russia to fulfill two of its current major goals: ensuring that EU sanctions are lifted, and building the foundations for fulfilling the Kremlin's long-term goal of making Ukraine, at the very least, a neutral buffer state. European leaders — most important, Hollande and German Chancellor Angela Merkel — have warned the Kremlin publicly that meaningful, high-level negotiations and the lifting of sanctions cannot occur until Russia demonstrates that it plans to take concrete steps to implement the Minsk cease-fire agreement. A summit scheduled for Jan. 15 in Astana that was to include the Russian, German, French and Ukrainian presidents was canceled because of European concerns about Russia's failure to take steps to de-escalate the fighting in eastern Ukraine. Moreover, the European Union is not scheduled to begin making decisions on easing sanctions until March, when the first of several rounds of sanctions expires. Thus, any concessions from Russia at this time would not lead to an immediate lifting of sanctions. Russia will delay any de-escalation until it would elicit concrete steps from Europe to lift sanctions.
The Nature of Moscow's Influence Over Separatists
The relationship between policymakers in Moscow and separatist groups in Donbas has contributed to the new uptick in violence. The separatist movement has remained highly dependent on Russia for arms and equipment and would not be able to act as an effective force or retain the territory it currently controls without continued and active support from Russia. The Kremlin fully controls the separatists' overall strategy, but it does not control each move the separatists make. Russia has "negative control" over the separatist fighters, allowing them to act within limits defined by Russia's political goals.
The Kremlin has acted repeatedly to ensure that the separatist groups remain responsive to Russian guidelines. Before the Dec. 9 de-escalation, Russia modified the command structures in the rebel groups, replacing leaders or joining commands under Russian leadership, to ensure that the separatists continued fighting within what the Kremlin considered acceptable parameters. Yet tactical decisions on the battlefield in eastern Ukraine are often reactive and are made by local commanders without Moscow's direct involvement.
Moscow can intervene and shape local forces' actions, but this does not rule out actions that serve the interests of local groups rather than the Kremlin — and those interests do diverge at times. For example, some local separatist leaders have expressed a desire to expand their territory to other cities in eastern Ukraine — a goal that the Kremlin, faced with political and financial constraints, rejects at this time. Even though Russian forces are present in eastern Ukraine, the separatist militias still make up the larger percentage of forces, with the latest estimates suggesting that there are about three times as many separatist fighters as Russian troops. Although the armed separatist movement is not viable without direct support from the Kremlin, ensuring that the separatists remain responsive and useful to Moscow requires the Kremlin to spend a great deal of political and financial capital.
As negotiations progress and Russia seeks to improve its position, and as local separatist groups remain active along the contact line, violence levels could fluctuate, with the Kremlin determining the separatists' strategic direction and preventing a full-scale escalation that could prompt new sanctions. In the long run, amid declining oil prices and growing financial troubles, the Kremlin will work to reduce tensions in eastern Ukraine in an attempt to lessen the economic impact of sanctions and general isolation from the West.