Russia has severe budgetary constraints, and the United Nations is pressuring both sides to respect the peace settlement. So why is Moscow reheating the frozen conflict in Ukraine?

On April 29, a senior U.N. official reported that pro-Russian unrest in Ukraine had escalated to its highest point since August 2014 — and that the conflict in eastern Ukraine claimed 173 lives in April alone. This uptick in violence has sparked fears for the fragile truce established by the February 2015 Minsk II accords.

Ukrainian and Russian officials disagree fiercely over who is violating the Minsk peace agreement. But Ukrainian intelligence reports provide evidence that Moscow deployed fighters and military equipment to Donetsk and other Russian-occupied cities.

Here’s why the hostilities are escalating:

1) Moscow wants to assert its control over eastern Ukraine

Recent cease-fire violations suggest that Moscow wants to call the shots on political developments in eastern Ukraine and keep pro-Russian brigades in line.

The Ukrainian Defense Ministry’s intelligence department recently reported that Vladislav Surkov, a close aide to Russian President Vladimir Putin, privately met with Alexander Zakharchenko, the leader of the partially recognized Donetsk People’s Republic. In that meeting, Russian officials reportedly criticized Zakharchenko for not following the instructions of the Russian military command. In particular, Russian supervisors reportedly complained that Zakharchenko’s rebel army had not used Russian financial and military aid for the combat purposes that Moscow intended. Zakharchenko also drew criticism from Moscow for not doing enough to oust Ukrainian troops near the town of Avdiivka.

Russia’s provisions of military support to its separatist proxies in eastern Ukraine don’t seem to be aimed at expansion, however. Instead, Putin appears to be launching small-scale military campaigns to determine which pro-Russian separatist brigades are loyal to Moscow. As Columbia University professor and leading Russian foreign policy expert Robert Legvold argued last fall, the prospect of a Russian military assault on Odessa or Kiev has faded considerably.

Instead, Russia’s military command chain is looking to consolidate control and discipline — in part because being more assertive in eastern Ukraine entrenches Russia’s hold over Donbas. In January, Putin appointed former interior minister Boris Gryzlov as Russia’s representative on the contact group established by the Minsk accords. The appointment of a senior Putin ally demonstrates the importance of reasserting Russia’s authority over Donbas.

The Kremlin is also taking charge of economic reconstruction efforts in Donbas, rather than leaving this task to Russian private enterprises. Sergey Nazarov, a federal deputy minister specializing in regional economic development, spearheaded a major development project covering the financial, energy, transportation and trade sectors of Donbas. Claiming dominance over Donbas’s military, bureaucratic and economic institutions, even if it requires the tactical use of small-scale military forces, bolsters Russia’s international status and world-power aspirations.

2) Russia sees Ukrainian politicians as threatening the cease-fire

While Russia and pro-Kremlin separatists are primarily responsible for the hostilities destabilizing eastern Ukraine, European leaders have also criticized Ukrainian policymakers for their unwillingness to support the cease-fire. German Foreign Minister Frank-Walter Steinmeier in March claimed that Kiev and Moscow are jointly responsible for the deteriorating security situation. Kiev’s lack of progress on removing heavy weaponry or pushing forward on planned prisoner exchanges are particularly problematic issues, as is the failure of amnesty efforts to come to fruition. Ukraine has also been resistant to holding elections in the separatist-occupied regions, a key term of the Minsk accords.

These failures are the result of recent political turmoil, as well as deep partisan polarization in Ukraine. Moscow has been keen to exploit these problems, blaming Ukraine’s slow political reforms for the recent escalation of tensions. Putin has pressured the Ukrainian parliament to pass sweeping constitutional reforms mandated by Minsk II. These reforms would grant Donbas permanent special status by law, a major symbolic victory for Russia’s efforts to consolidate its authority over eastern Ukraine.

But nationalists and populists in the Ukrainian parliament continue to block these reforms. These factions are inspired by the rhetoric of such political leaders as former prime minister Yulia Tymoshenko and ex-Georgian president Mikhail Saakashvili and by far-right groups such as Right Sector. Putin perceives these leaders to be even more anti-Russian than Ukraine’s current president, Petro Poroshenko.

These groups are growing more popular in Ukraine, thanks to their anti-austerity stance and criticism of Poroshenko’s failure to combat corruption. And they now have more bargaining power domestically. Tymoshenko has criticized decentralization measures in the constitutional reform package that she views as favoring Russian interests. Last summer, a number of far-right nationalists openly called for the breakdown of the cease-fire process and demonstrated against Minsk’s implementation.

This growing political clout has extended to the international arena. Vladimir Frolov noted in a recent Moscow Times op-ed that Russian officials strongly disapproved of tentative German support for Ukrainian lawmakers seeking to decouple constitutional reforms from the Minsk mandate. Extrapolating from past rhetoric, it is logical to assume that Russia views the growing doubts about Ukraine’s willingness to uphold the Minsk accords as legitimate justification to reignite hostilities in Ukraine.

 3) NATO has a growing military presence in the Black Sea

The fear of NATO encirclement also helps explain Russia’s escalation of military hostilities in Ukraine. In recent months, Pentagon officials worked to expand the U.S. and NATO military presence in Eastern Europe. U.S. defense spending in Europe will bump to $3.4 billion in 2017 to include an upgraded NATO weapons stockpile and create a rapid-reaction force to defend Eastern Europe against potential Russian aggression.

NATO members support an increased NATO presence in the Black Sea. Turkish President Recep Tayyip Erdogan, who is on hostile terms with Putin, recently expressed concerns that NATO needs to be able to counter Russian control over the coast. Romania, with similar concerns, welcomed the U.S. decision to deploy F-22 fighter jets to Bucharest in late April.

In February, Russia staged massive military exercises near Crimea — a clear indication of Putin’s concern about NATO’s increased presence. Russia’s Defense Ministry declared that the mobilization of 8,500 troops and more than 1,000 units of military hardware was necessary to defend Russia.

In recent months, instances of Russian jets flying uncomfortably close to NATO warships have become more frequent. As Crimea and its naval base of Sevastopol are of vital strategic importance to Russian hegemonic ambitions in the region, Moscow expects a stronger Russian military influence in Ukraine to deter further “NATO provocation” in the Black Sea.

In short, Russia’s escalation of hostilities in eastern Ukraine can be explained by a desire to consolidate its influence over the territories it occupies, along with pushback against perceived Ukrainian and NATO belligerence.

What’s next? There will probably be a short-term tactical increase in military conflicts, followed by the reestablishment of a frozen conflict. But even if these hostilities are of short duration, the Minsk accords’ future and peace prospects in Ukraine hang nervously in the balance.

Samuel Ramani is a master of philosophy student in Russian and East European studies at St. Antony’s College, University of Oxford, specializing in post-1991 Russian foreign policy. He can be followed on Facebook at Samuel Ramani and on Twitter @sramani2.