People march with an Armenian flag during a rally on April 5 in memory of those killed during fighting in Nagorno Karabakh’s main city of Stepanakert. (Reuters)

In early April, the volatile conflict in Nagorno-Karabakh erupted in violence. Four days of heavy fighting between Azerbaijani and Armenian forces over this disputed region resulted in at least 200 casualties. Even though both sides avoided escalation into a full-scale war, the halt in hostilities is fragile, and the conflict could easily accelerate anew.

U.S., Russian and French officials met with the Armenian and Azerbaijani presidents in May to push for a non-military solution. The two leaders are scheduled to meet in June to resume talks on a comprehensive settlement, but this will prove an uphill struggle. Two decades of talks have failed to produce a breakthrough, and the four-day war further undermined the hope of a compromise solution. It has strengthened hard-line forces on both sides and validated the use of force.

On the Azerbaijani side, it has emboldened those who insist on the legitimacy, and feasibility, of the forceful reintegration of Nagorno-Karabakh. On the Armenian side, it has strengthened the resolve not to withdraw troops from the districts surrounding Nagorno-Karabakh or accept any solution that does not guarantee full independence. The escalation has increased fears and deepened mistrust. Both sides fear that the other side would take advantage of, and manipulate, a settlement and both fear that their communities will be left at the mercy of the perceived enemy.

Forcing concessions may have caused the latest violence

It’s not entirely clear what set off the April hostilities, though a likely cause was an Azerbaijani push to test the Armenian defenses and persuade Armenian negotiators to make concessions at the negotiating table. Azerbaijan is deeply frustrated with the status quo and the de facto loss of a significant part of its territory — and has equal frustration with the peace process that has dragged on for years with little result.

The recent fighting appears to have shifted the front line in Azerbaijan’s favor. This is significant, but not because the reclaimed territory is strategic or sizable. The Azerbaijani gains dealt a blow to Armenian pride, but more importantly, they signaled that Nagorno-Karabakh’s position is perhaps not as secure as the entity’s leadership believed it to be or as strong as they have portrayed it to their public.

While the escalation clearly unsettled the Armenian side, it also seemed to confirm the existing military stalemate. Even if the escalation has made this stalemate more costly, or more risky, to the Armenians, this would still not be enough for a negotiated settlement.

There are two key obstacles standing in the way of a Nagorno-Karabakh peace settlement:

1. It’s a tough sell domestically

My research on this conflict discusses the problem of domestic constraints. Even if the Armenian and the Azerbaijani presidents push hard for a compromise deal, neither party is likely to find much support, either within their respective governments or publics. Both sides have seen increasingly shrill rhetoric, with virtually no discussion of alternative positions or conciliatory options. Both sides have used the conflict for propaganda purposes, painting the other side as “the enemy,” which makes compromise difficult.

Armenian leaders who appeared to take an overly moderate position in the peace talks then experienced domestic backlashes — most famously when Armenian President Levon Ter-Petrosyan was forced out in 1998 — and will be well aware of the risks of appearing to back down.

Foreign policy experts generally see Azerbaijan’s president, Ilham Aliyev, as a stronger leader than his Armenian counterpart. Since coming to power in 2003, Aliyev has consolidated his position and cracked down on any opposition, but he may still have little room to maneuver. His country remains in an economic crisis. And the four-day war sparked a bout of nationalist euphoria, with Azerbaijanis excited over their perceived victory. This reinvigorated nationalistic pride does not bode well for the difficult trade-offs a peace settlement would necessarily entail.

2. No appetite for cohabitation

The proposed solution is the second obstacle. The principles that have formed the basis of the talks since 2005 would postpone the final status of Nagorno-Karabakh. In the meantime, Armenian forces are to withdraw from the districts surrounding the region, refugees and displaced persons are to return, and Nagorno-Karabakh is to enjoy an internationally guaranteed interim status. There is no agreed-to timeframe for this. A legally binding “expression of will” will then decide their final status.

The Armenian side interprets this as an independence referendum within the disputed region. But Azerbaijan rules this out and insists that full independence cannot be an option. When Russian Foreign Minister Sergei Lavrov recently stated that all the components of an agreement were on the table, this is what he referred to. But the two sides do not agree on the interpretation of the components, in particular the “expression of will,” or their sequencing.

Other countries, including Sudan, Bougainville in Papua New Guinea, and Serbia and Montenegro, have tried this approach with some success — but with one key condition: Divisions within the separatist territories meant that the outcome of the independence referendum was not a foregone conclusion. This meant that territorial unity could conceivably be made an attractive option to voters.

This is not the case in Nagorno-Karabakh. When it comes to independence, we find almost complete unanimity within the entity. No political forces question the need for independence, and polls suggest that the vast majority reject any future association with Azerbaijan. The Azerbaijani government has, despite its insistence on reintegration, made no effort to try to reach out to the Karabakh Armenians to build trust.

So a vote in Nagorno-Karabakh would therefore be entirely predictable, and the interim period would achieve little. One option would be to require a super or double majority in the referendum, Instead of the usual 50 percent threshold, the referendum could specify that a proportion of returning Karabakh Azeris would also have to support independence. But the Armenian side also has not presented any convincing vision of cohabitation within Karabakh, and such a requirement would result in an equally predictable, and dangerous, deadlock.

Both sides have serious trust issues

The four-day war and the reported atrocities further deepened this problem: Both sides are even more convinced that the other side harbors nothing but harmful intentions.

A possible way out of the deadlock could be a more vague agreement, one that simply postpones the final status, without promising an independence referendum. Both the Chechen and Israel-Palestinian conflicts took this approach, but their agreements did not prove sustainable, so this is not likely the best model to emulate. And both of those agreements were in any case based on a balance of power tilted in favor of the central government.

Such a balance of power is not found in the Nagorno-Karabakh conflict — and this kind of ambiguous agreement is unlikely to be accepted by the Armenian side. The Karabakh leaders are in a much stronger position than the Chechen and Palestinian leaders were and are not likely to gamble their de facto independence on such a risky settlement. They are convinced that Azerbaijan would use the interim period to forcefully reintegrate the region. The latest escalation has done little to dispel such fears.

Nina Caspersen is the author of “Unrecognized States” and the forthcoming “Peace Agreements” (both Polity Press). She is a senior lecturer of politics at the University of York in Britain. This article draws on her British Academy-funded project on peace agreements. Follow her on Twitter: @NinaCaspersen