EUROPE’S 26-nation borderless zone, Schengen, has been under pressure since August. The unprecedented number of migrants entering it in search of a better life caused many states to ask for reinstallation of border controls earlier this year. After the Paris attacks, revisiting the agreement became even more urgent. Some countries closed their borders, a measure Schengen allows for reasons of national security; others are lobbying for a long-term interruption of the agreement. But despite the area’s uncertain future, last week expulsion was still used as a threat towards one member state, Greece, which refused to co-operate in the collective effort to alleviate the refugee crisis. Why?

The first sign of a bust-up came on November 27th, when Slovakia’s prime minister, Robert Fico, said that European leaders were keen to shoo Greece out of the visa-free zone. Frustration with the country, which entered Schengen in 1992, had mounted after it refused EU help in controlling its external borders and curbing the migrant influx. Greeks reacted to the possibility of being pushed out of Schengen with consternation. Riots between migrants and refugees trapped at Greece’s northern border with Macedonia added to the pressure. By December 4th Greece had agreed to let Frontex, the EU’s border agency, carry out patrols and to accept EU humanitarian aid for people stranded on islands and other land-border areas.

Suspending Greece from the Schengen zone would not do much to limit the number of migrants crossing into the rest of Europe. Greece has no borders with other Schengen-zone states, so for refugees travelling by land it would be no easier or more difficult to make the journey than before. The only consequence would be to deprive Greek citizens of the right to travel freely within Schengen and, perhaps more importantly, to force overseas visitors to obtain a visa to enter Greece—a blow to Greece’s tourism-reliant economy. At a meeting of European interior ministers in Brussels on December 4th, where the introduction of a passenger name record was also discussed, Greece was not suspended. Instead, the entire 30-year-old Schengen agreement itself was. Ministers decided to press ahead with plans to reinstall border checks for up to two years.

It may seem odd that Greece would cave in to the pressure of being expelled from Schengen at a time when the zone’s future itself is uncertain. Yet border checks in Europe, whatever their practical use, are important symbols of who belongs to the club and who does not. The case of Schengen and Greece’s future in it will be revisited in March 2016, when members will consider a longer-term suspension. For now, the continent is struggling to find a way to manage its migrant and border problems without dissolving the project of European unity.