The heightened perception of a Russian threat to the West could have at least one positive consequence: The admission of the former Yugoslav Republic of Macedonia to the European Union. But the massive rallies in Athens on Sunday, with at least 140,000 protesting against the Greek Government’s apparent willingness to compromise on Macedonia’s name, show that the 26-year-old issue is not about to fade away.

Ever since Yugoslavia broke up in 1991, Macedonia has lacked a permanent official name because Greece has maintained that its northern province is the rightful Macedonia, the cradle of Alexander the Great’s Greek-led empire. Greek and Bulgarian historians have long claimed that the population of Macedonia — a territory that has been, off and on, under Bulgarian control — is essentially Bulgarian, with little claim on the ancient Greek heritage, and that Cyril and Methodius, the inventors of the Cyrillic alphabet and part of Macedonia’s pantheon of national heroes, were born of a Greek father and a Bulgarian mother.

In Macedonia itself, however, the dominant view — fostered throughout the existence of Iosip Broz Tito’s Yugoslavia and by later nationalist governments — is that the country has a distinct national identity and full rights to the Macedonia name. The airport in Skopje, the capital, is named after Alexander the Great, and a majestic statue in the city’s central square is known to be of him, although it is not labelled. Cyril and Methodius are honoured as locals. These claims have been an essential part of the Government’s nation-branding efforts aimed at putting Macedonia on the map as a tourist destination.

Northern Greece, with a tourism industry built around Alexander, has resented the competition, and politicians in Athens have long feared cultural claims would lead to territorial ones; Greece and Macedonia alike have put “Welcome to Macedonia” signs on their sides of the border. Greece has vetoed Macedonia’s attempts to get into the EU (it’s been an accession candidate since 2005) and the North Atlantic Treaty Organisation, demanding that it drop its claims to the Macedonia name first. In Macedonia itself, significant majorities want to join both blocs, but they shrink dramatically if a name change is required for accession.

US diplomat Matthew Nimetz, who has been trying to negotiate an end to the dispute since 1994, first on behalf of the US Government and then as a United Nations special envoy on the issue, has argued that resolution would be a matter of timing. And, thanks to Russian President Vladimir Putin’s recent behaviour, a window of opportunity has been created.

Since Russia annexed Crimea from Ukraine in 2014, there have been fears of Kremlin meddling in the Balkans, a traditional Russian sphere of influence thanks to historic ties with Serbia. Pro-Russian sentiment is still high in Serbia today, and the country’s current government tries to reconcile that sentiment with a desire for EU membership, much as the pre-2014 Ukrainian government unsuccessfully attempted to do.

Prosecutors in Montenegro have accused the Kremlin of being behind an attempted coup in that country in October 2016 to prevent it from joining Nato (it joined last year). And a Russian presence has long been felt in Macedonia; according to recently leaked Macedonian intelligence files, the Kremlin has been trying to spread propaganda and provoke discord, pushing the country away from a westward path.

This put pressure on both the EU and Nato to resolve the name dispute as quickly as possible. Given Greece’s status as a ward of the EU, it was perhaps to be expected that Greek Prime Minister Alexis Tsipras would be willing finally to accept a compromise. At the same time, Macedonia has had a pro-Western government since last year. Prime Minister Zoran Zaev has promised to advance EU and Nato membership talks and to work something out with Greece.

The compromise under discussion has been proposed without success before: Macedonia is to accept an adjective before the Macedonia name, as in “Upper Macedonia,” “North Macedonia” or “New Macedonia.” This time, perhaps it has a chance. Nato’s need to expand to counter Putin is driving the EU’s expansion into the Balkans — something that wouldn’t be a priority otherwise.

This window of opportunity has a flaw, though. Though the Greek public previously allowed Tsipras to bend to outside demands, allowing the neighbouring country to use the Macedonia name in any context may well be a red line. An economic policy dictated by creditors is, after all, temporary; Greece may even regain full access to international financial markets this year after last year’s bond sale. But many Greeks, who already feel humiliated by the recent damage to the country’s sovereignty, appear to be especially reluctant to allow a permanent concession on Macedonia.

New Democracy, the liberal party that currently leads in the polls, is not averse to an “adjective-plus” compromise itself — but it won’t vote with the Tsipras government on it, and it’s likely that the nationalist Independent Greeks party, part of the ruling coalition, won’t either. The influential Greek Orthodox Church — with its strong ties to the Russian one — has backed the protests. There’s even a possibility of a government crisis and an early election.

Under such circumstances, accepting a compromise with Tsipras may be tricky for Zaev, too: What if the next Greek government reverses it? If the window for a deal closes and Putin wins a surprise reprieve in the Balkans, history — both ancient and recent — will strike yet another blow at the postmodern European project.

• Leonid Bershidsky is a Bloomberg View columnist. He was the founding editor of the Russian business daily Vedomosti and founded the opinion website Slon.ru