BRUSSELS (AP) — European Union leaders failed Friday to agree on launching membership negotiations with Albania and North Macedonia in an embarrassing climb-down that could risk inflaming the volatile Balkans region.

The two countries had expected to receive a green light to begin negotiations on joining the European club, a process which could take several years.

The European Commission, which supervises entry talks, insists that both have met all the criteria for admittance. EU leaders had promised a final decision by the end of October.

For now, a decision is unlikely until May 2020 at the earliest.

French President Emmanuel Macron won’t allow any new countries into the 28-nation bloc until its enlargement procedures have been improved, while the Netherlands opposes Albania’s candidacy and disputes the commission’s assessment.

“The overwhelming majority wanted to open accession talks with North Macedonia and Albania. However, such a decision requires unanimity and there was no unanimity yesterday,” said EU Council President Donald Tusk, who chaired the meeting.

“Both countries, they passed their exams. I can’t say this about our member states,” he said.

The non-decision, he added, was “a mistake.”

As Britain prepares to leave the EU, its 27 partners have been at pains to show their unity. However, decision-making on important issues can be held hostage by just a few member countries.

Italian Premier Giuseppe Conte said the failure to open the EU enlargement process “will be remembered as an historic error.”

“I told my colleagues that this was an appointment with history. In 1400 those territories fell under the Ottoman Empire. After World War II they fell under the communist bloc. It is their aspiration to join Europe,” Conte told reporters.

“I hope that the despair doesn’t lead to the deepest distress.”

And former Greek prime minister Alexis Tsipras, whose decision to support North Macedonia’s change of name in an effort to set aside years of tension between the two countries lost him support, tweeted that the failure “is a message of weakness and defeat for the European project.”

The constant expansion of the EU over the years has complicated decision-making in the world’s biggest trade bloc, and “enlargement fatigue,” as some have termed it, has set in. Turkey’s membership talks, for example, are virtually frozen.

The EU has always said that membership is based on a candidate’s merits.

Albanian Prime Minister Edi Rama regretted the deadlock. He said it “is linked with an open confrontation within the EU itself,” on its enlargement process and internal debate.

“The process of European integration will continue. Not because Paris, Berlin, Brussels or all of them are asking for it, but because it is needed to turn our country into a European, functional one,” Rama said on a talk show late Thursday after returning from Brussels.

In a televised address, North Macedonia’s president Stevo Pendarovski urged the nation not to be “disappointed.”

“This is not a time for disappointment and apathy, but time for national unity. I’m convinced that if we are working together, we will succeed,” Pendarovski said.

“We have the right to be part of common European home.”

EU foreign policy chief Federica Mogherini warned in May that any failure to recognize the efforts of the two countries “undermines stability and seriously discourages further reforms.”

Her warning came just after Serbia put its troops on full alert when heavily armed Kosovo police fired tear gas and arrested about two dozen people in Serb-dominated northern Kosovo in what they called an anti-organized crime operation.

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By LORNE COOK Associated Press

Colleen Barry in Milan, Llazar Semini in Tirana, Albania, Konstantin Testorides in Athens, and Samuel Petrequin in Brussels contributed to this report.