Turkish Cypriot demonstrators wave Turkish and Turkish Cypriot flags during a mass rally in support of Turkey’s Prime Minister Recep Tayyip Erodgan following a failed coup that aimed to oust him. Peace talks aimed at reunifying north and south Cyprus resume Jan. 8. (Philippos Christou/Associated Press)

On Monday, negotiators will reconvene to try to resolve a four-decade standoff on the island of Cyprus. Since 1974, the island has been divided between north and south. Even its capital city of Nicosia is split in two by the “green line” that divides the Republic of Cyprus, which identifies as Greek, from the Turkish Republic of Northern Cyprus (TRNC).

Why? In 1974, after a Greek military coup, Turkey invaded the northern part of the island to secure autonomy for Turkish residents. Since then, Turkey has supported the breakaway nation while the European Union and United Nations have pressed for reunification. In November, the two sides seemed close to peaceful reunification — until talks collapsed.

While the conflict has been peaceful in recent years, the lack of resolution holds back both sides. For decades, the E.U. and U.N. have imposed economic sanctions on TNRC to try to force it back into a union with Greek Cyprus. The sanctions have crippled the TRNC economically. The south suffers as well, as the standoff discourages international investment and slows development.

Almost any of the proposed agreements could make both sides better off. So why is a deal so elusive?

The state of the deal

To get the TRNC to agree to reunify with the south, the proposed agreement promises many things to the north. These promises include the end of sanctions, a presidency that rotates between Turkish Cypriots and Greek Cypriots, and other political arrangements that guarantee Turkish Cypriots a voice in the new government.

But of course, Greek Cypriots could simply renege once the island is reunified and the Turkish military withdraws from the north.

In 1994, separatists in Gagauzia agreed to rejoin Moldova in exchange for promises of regional autonomy. The autonomy was initially granted. Then in 2002 the Moldovan government forced the governor from office, jailed several other Gagauz politicians and reasserted control.

How to enforce the deal, then, is the question that must be solved to get an agreement. How does the TRNC seize the economic benefits of reunification, while avoiding the fate of the Gagauz separatists in Moldova?

Stalemated separatist conflicts are really tugs of war between the foreign backers of each side

In a newly published paper in the Journal of Law, Economics and Organization, we show that stalemated separatist conflicts, such as the one in Cyprus, can be understood as a push and pull between the foreign powers that support each side.

Stalemates continue when the outside actor supporting the separatists — here, Turkey — considers the issue to be more important than do the actors supporting reunification — here the E.U. and the U.N.

Our analysis suggests that, if the E.U. and U.N. are willing and able to commit sufficient resources, a peaceful, durable resolution is possible.

Because reunification agreements are so difficult to reach and enforce, reunification in similar cases has been most often achieved through military conquest. Throughout negotiations, most of the focus has been on the presidents of the Republic of Cyprus and the TRNC. But in fact, the fate of reunification hangs primarily on whether outside countries and institutions will make commitments to support the deal.

What motivates each international backer?

The E.U. wants reunification of the island, not independent statehood for the TRNC. That’s because many countries in Europe have a region or two that separatists want to split off into another country such as Catalonia and the Basque region of Spain; Flanders in Belgium; and Corsica in France. If the TRNC gains independence, it would embolden separatist groups across Europe.

The economic embargo has been intended to force the TRNC to the bargaining table. The carrot in this arrangement is that, in addition to lifting the embargo, reunification would grant the region access to E.U. markets and development aid. Previewing the benefits of reunification, since 2004 the E.U. has offered all Cypriots — including residents of the TRNC — E.U. passports.

Turkey, in contrast, is seeking to undermine current negotiations, hoping instead for independence for the TRNC or a chance to annex the territory, as Russia recently did in Crimea. Even persistent stalemate allows Turkey to wield enormous influence over the region, influence that would evaporate if the island reunifies.

Turkish troops protect the island from any attempts at military conquest by the Greek Cypriots, and Turkey works to prop up the economy of the north enough to ensure that reunification does not become too appealing.

In October, Turkey and the TRNC signed an agreement to integrate their electric grids, and are pushing forward a range of infrastructure and energy-related collaborations. But even with Turkish support, the TRNC is barely scraping by. Incomes in the north are 40 percent lower than in the south, and growth is stagnant.

So how can the foreign powers’ standoff be undone?

If the E.U. could offer Turkey a credible path to membership, then it might be able to persuade Turkey to stop supporting independence for the TRNC. But in November, the E.U. Parliament voted again to slam shut the door on Turkish accession.

The E.U. must therefore promise to enforce political autonomy for the North after reunification — by, for instance, threatening to impose sanctions on the Cypriot government if it fails to live up to the deal. That way the TNRC representatives can be confident that Greek Cypriots won’t be allowed to run roughshod over the North as soon as Turkish troops withdraw. This is a commitment the E.U. is powerful enough to make — if it has the will to do so.

Kristy Buzard is an assistant professor of economics at Syracuse University’s Maxwell School of Citizenship and Public Affairs.

Benjamin A.T. Graham is an assistant professor of international relations at the University of Southern California.

Johanna Reyes is a research intern in the Security and Political Economy (SPEC) Lab at the University of Southern California.