German Foreign Minister Annalena Baerbock has called for the rapid admission to the European Union of accession candidates in the Western Balkans as the bloc marks the 20th anniversary of its enlargement by 10 countries in 2004.

“Political and geographical ‘grey areas’ in the Balkans or in the east of the EU are extremely dangerous,” Baerbock wrote in an opinion piece published to mark the anniversary.

“We cannot afford such grey areas, because for [Russian President Vladimir] Putin they are an invitation to interfere, to destabilize,” Baerbock said.

The article, which dpa saw in advance of publication, appears on Monday in media in Lithuania, Latvia, Romania and Greece.

Estonia, Latvia, Lithuania, Poland, the Czech Republic, Slovakia, Slovenia, Hungary, Malta and Cyprus were admitted to the EU on May 1, 2004.

“We have known at least since Russia’s war of aggression against Ukraine: The enlargement of our EU today is also a geopolitical necessity,” Baerbock wrote.

Just like 20 years ago, millions of Europeans today see an opportunity and promise in becoming EU citizens.

“We cannot afford to have another entire generation languish in the EU waiting room again, as was the case in the Western Balkans,” she warned.

“We must not squander the opportunity to make our union bigger and stronger – and therefore more secure.”

The generation of the 2004 enlargement round had to summon up the courage “not to be swayed by headwinds and populist slogans,” Baerbock said.

“Our generation is now faced with the task of defending and strengthening the European project of peace and freedom, even if it costs an incredible amount of energy.” Reforms are necessary for this to succeed, she said. This also includes fewer veto options in the European Council.