In 1971, CIA personnel wrote a 12-page document titled “The Macedonian Syndrome.” Released 40 years later, it stands the test of time as a transparent analysis of one of Southeast Europe’s most intractable historical conflicts. Its authors will perhaps not be surprised to learn that, despite the different geopolitical context of our time, the tensions over Macedonian identity evoked in the document by the American intelligence agency remain as unresolved today as they half a century ago.

For these reasons, it is premature to celebrate this week the EU’s launch of the negotiation process whereby North Macedonia — and Albania — can in principle join the bloc. Of course, any progress seems better than none. North Macedonia was nominated as a candidate for EU membership in 2005, under the name of the former Yugoslav Republic of Macedonia. Albania has held candidate status since 2014. Just bringing them one inch closer to EU membership is better than leaving them languishing in the antechamber indefinitely.

Still, the unusual conditions attached to North Macedonia’s European route are causing concern. Courageously, European leaders responded to Russia’s attack on Ukraine by conferring candidate status on Ukraine and Moldova last month. They also sped up the process for North Macedonia and Albania, lest they be seen as neglecting the Western Balkan states that have been knocking on the door for much of this century. But in their rush to do the right thing, EU leaders have piled up problems for the future.

Essentially, they’re inviting North Macedonia to join, but saying it won’t happen unless it meets a stringent set of requirements set out by its neighbor Bulgaria. These relate mainly to language, national identity and history. At any stage of the entry talks, Bulgaria has the power to stop or delay them by declaring that North Macedonia is evading its obligations.

Bulgaria’s requirements go well beyond the formal EU admission criteria. These are mainly aimed at complying with EU standards on market economy and democracy and at integrating EU legislation into national law. To join the EU, no previous candidate has ever been forced to give in to another country’s demands on issues such as interpretations of history which can never have a permanent and definitive answer. But Bulgaria is in the EU, having joined in 2007, and North Macedonia is a supplicant. The uncomfortable truth is that Sofia holds the upper hand.

By endorsing Bulgaria’s position, the EU – which believed it was the only way forward – not only stood down as an impartial arbiter between the two countries, but made it likely that similar obstacles are faced by other Western Balkan countries. For example, a dispute erupted this month between Croatia, which is part of the EU, and Serbia, which is a candidate, over a planned visit by President Aleksandar Vučić of Serbia to an atrocities site. Croatians versus Serbs in World War II. What if one day Croatia followed Bulgaria’s example and demanded that Serbia accept a Croatian reading of the history of Yugoslavia in the 20th century?

In defense of the EU, North Macedonia’s parliament last week approved a protocol that includes Bulgaria’s conditions. But that’s only half the story. Sofia insists that her neighbor must change its constitution to give official status to the Bulgarian minority in North Macedonia. This will require a two-thirds majority in parliament, which currently seems a distant prospect.

The problem of minorities sums up the unilateral approach of the EU. North Macedonia will have to amend its constitution, but Bulgaria has no obligation to enshrine the rights of its Macedonian minority, despite numerous rulings by the European Court of Human Rights in favor of this community.

In truth, each party must display a better understanding of the other. Since the rise of modern Macedonian national consciousness in the 19th and 20th centuries, Bulgaria has struggled with the very concept of a separate Macedonian nationality. When Yugoslavia broke up in the 1990s, Bulgaria was the first country to recognize the new Macedonian state. But he does not recognize the Macedonian language, considering it a branch of Bulgarian. The 1971 CIA document observed: “Sofia claims that all Macedonians are really ethnic Bulgarians cut off from the homeland.”

In North Macedonia, some nationalists no doubt sound like they are making territorial or cultural claims on their neighbours. This is why it was vital that the country settle its differences with Greece in the 2018 Prespa agreement. However, by granting its favor to Bulgaria over North Macedonia, the EU may have by inadvertently halted the work of the Balkan enlargement project which it claims to support.

tony.barber@ft.com