Perched dramatically on the hill above the Slovak capital of Bratislava stands Bratislava castle, once the royal seat of the Hungarian empire.

The location of yesterday's meeting of European Union leaders was rich in symbolism. For decades Bratislava lay just behind Europe's iron curtain, its people restricted from visiting the Austrian capital Vienna just an hour west along the Danube river.

While Bratislava's location straddling the old border between east and west Europe is a powerful reminder of how far the continent has come since the fall of communism, it also suggests the new challenges facing the EU.

The last year has seen unprecedented divisions between Europe’s central and east European countries on the one hand and the EU’s older member states on the other over the refugee crisis.

Slovakia – and its prime minister Robert Fico who said his country would only accept Christian refugees – was one of the most strident opponents of the European Commission's proposal for a refugee relocation plan.

Through the forum of the Visegrad group – an informal alliance of Poland, Hungary, the Czech Republic and Slovakia which meets regularly before summits – these countries are becoming an increasingly powerful voice.

Resentments over the European Commission's relocation plan – pushed through the EU legislative process against the will of many central and east European member states through qualified majority voting – still linger. Hungary has joined Slovakia in bringing a legal challenge to the proposal, while Hungarian prime minister Viktor Orban has called a referendum on the issue early next month.

Mistakes of others

Tensions threatened to spill over after Luxembourg’s foreign minister

Jean Asselborn

said in a newspaper interview Hungary should be thrown out of the EU for its handling of the refugee crisis. His comments provoked a furious response from

Budapest

, with the Hungarian government arguing it should not take on the “burden created by the mistakes of others”, before taking a jibe at Luxembourg’s taxation.

Preventing divisions was one of the key challenges for European Council president Donald Tusk yesterday, as the EU attempted a show of unity in the wake of Brexit.

Tusk visited Warsaw and Budapest in the days preceding the summit. As a former Polish prime minister, he understands the concerns of former Soviet bloc countries, and his decision to prioritise security and the need to strengthen the EU's external borders could be seen as a response to their concerns.

Commission president Jean-Claude Juncker appeared to strike a conciliatory note in Strasbourg on Wednesday, suggesting solidarity on the refugee crisis must "come from the heart".

Coherent idea

Nonetheless, the EU is struggling to present a coherent idea of what the union should be, following Britain’s decision to leave.

While central and east European countries are prioritising security threats and the refugee crisis, others have different ideas.

As the Visegrad group were meeting in Warsaw this week, Greek prime minister Alexis Tsipras convened a mini-summit of Mediterranean countries including Italy, Spain and France in Athens, where he led calls for a more social economic model for Europe.

A day before the Bratislava summit, German chancellor Angela Merkel met her French counterpart François Hollande in Paris for talks that underlined the strength of the Franco-German alliance, with both backing calls for a stronger EU defence policy.

Where Ireland fits into this fragmented picture is unclear, though Irish officials have been aligning themselves with the Netherlands, Nordic and other northern states by calling on the EU to pursue economic growth and ensure the union remains a free-market economy, open to foreign investment, in the wake of Brexit.

While yesterday’s summit marked the start of the conversation about Europe, there have been calls for consideration of a multitiered EU, built around a core who want to integrate further, and a looser constellation.

Former Belgian prime minister Guy Verhofstadt, the European Parliament's negotiator on Brexit, has called for an "associate member" class, which could also apply to Britain, allowing other states to integrate further.

How the EU develops and where Ireland positions itself are questions for coming decades.As the 27 flags flew over Bratislava Castle, the British flag was absent for the first time in 43 years. Already, the EU is looking towards a future without Britain.