IDOMENI, Greece — The European Union’s weakest link could become an open-air refugee camp if some European leaders get their way. Amid concerns that Greece is failing to protect Europe’s external frontier, calls have grown louder to quarantine it by helping Macedonia seal its southern border — which refugees must cross to continue their journeys north — and suspend Greece from the EU’s passport-free Schengen zone.

Such proposals would effectively ring-fence Greece from the rest of the EU, trapping tens of thousands of asylum-seekers in a politically and economically fragile country with neither the infrastructure nor funds to care for them. Most migrants know this. Hence, Greece has never been their destination. It is merely a conduit to more affluent nations deeper into the continent.

More walls around Europe will not stop them. Rather, they will find other routes or be driven further underground.

The Greek border town of Idomeni offers a glimpse into what Greece’s refugee crisis will become if the country is cut off from the rest of Europe. The border crossing and transit camp, located along the railway tracks connecting Greece and Macedonia, has emerged as a tense choke point for migrants traveling northwest through the Balkans.

Smugglers controlled this area long before Europe’s migration crisis exploded last year. Those mafias “disappeared totally” last summer, when Balkan nations including Macedonia began allowing all asylum-seekers 72 hours to traverse their countries legally, according to Antonis Rigas, a field coordinator for Medecins Sans Frontieres (MSF) at Idomeni. For the first time, a “humanitarian corridor” to Germany was open, and the route arguably safer than ever before. It was chaos, of course, but controlled chaos, with tens of thousands entering and exiting Greece in a matter of days.

That all ended in late November. In a bid to keep out “economic migrants,” Macedonia and other western Balkan countries said they would admit only Syrians, Afghans and Iraqis, who are likelier to fall under the legal definition of a refugee. Greece had no say in this nationality-based filter of questionable legality — and it had no choice but to deal with the thousands stranded in Greece because of it. At Idomeni, violent protests broke out among the thousands of “others,” who came from countries such as Morocco, Iran, and Somalia. And smuggling activity has roared back, aid workers and volunteers say.

Greece, crippled by six years of austerity, has been slow to systematically register the flow of migrants arriving on its Aegean islands — so much so that the European Commission said it found “serious deficiencies” in Greece’s protection of Europe’s external frontier. If these deficiencies persist within three months, Europe’s 26-member Schengen Area could vote to reimpose border controls for up to two years. This decision would effectively cut off Greece, which does not share a land border with any other Schengen countries, from the rest of the zone. The greatest impact for Greece would be economic, slowing the movement of people and goods at air and sea ports.

Meanwhile, some European leaders have already given up on Greece and are setting their sights on Macedonia and Bulgaria. Hungary and Austria are calling for reinforcement of the barbed-wire fence Macedonia built at Idomeni last fall. It is already causing bottlenecks of several thousand people on the Greek side as Macedonia opens and closes the crossing randomly, without warning.

This is how Greece, the entry point into Europe for more than 850,000 asylum-seekers last year, is already becoming a vast holding pen. It can do little to deter refugee boats from reaching its 8,498 miles of coastline — the longest in Europe. Once they reach Greek territorial waters, “pushbacks” would violate international law.

But if Idomeni is any indication, an era of closed European borders will just push those trapped in Greece to try ever more dangerous routes to get out. Groups like the UNHCR and International Organization for Migration encourage those blocked from traveling through Macedonia under the nationality-based filter policy to return to Athens, where they can apply for asylum or return to their home countries voluntarily. Determined to move on, many stay at Idomeni, sleeping in abandoned buildings or fields as they attempt to cross the border covertly.

Further, blaming Greece for Europe’s migration woes ignores the roots of the problem, in particular Syria’s ongoing war. Criminal networks in Turkey reaped millions sending refugees and migrants to Europe last year. The EU’s 3 billion-euro deal with Turkey to stop migration flows has made little difference in the number of arrivals to Greece so far. Severing the Balkan route at the Greece-Macedonia border without first stopping boats from leaving Turkish shores is playing directly into the hands of smugglers in Europe.

Another major problem is the lack of legal alternatives for refugees to reach Europe — or move within it once they arrive. The EU-Turkey deal focuses on keeping refugees in Turkey rather than letting them come to Europe safely. And the EU’s relocation scheme, which pledged to move 160,000 asylum-seekers from Greece and Italy to other European countries, has moved only 481 so far, the European Commission reports. Because of its slowness, few asylum-seekers choose to participate. According to the Greek asylum service, only 13 countries have made relocation slots available. So before Europe talks about walling off Greece, the relocation program, if it is to work, needs to be sped up and other EU members pushed to shoulder their share of the burden.

Further, Greece cannot afford food, medical care and shelter for those who would be stranded if its border with Macedonia is permanently sealed. The country has already spent more than 2 billion euros on the refugee crisis in the past two years. Six years of austerity have left it unable to provide medical and social services to many of its own citizens, let alone hundreds of thousands of foreigners who would be trapped indefinitely if its border was sealed.

For refugees escaping war and persecution, reaching their destinations in Europe amid ever more restrictive border policies is “like a video game,” said Faye Karavasili, an attorney from Vienna who quit her job to volunteer with refugees in northern Greece. “They fight their way through, but then they get to the next level and it’s a new set of obstacles.”

By circumstance of its geography, Greece is the frontline of Europe’s migrant crisis. Ring-fencing it from the rest of the continent will not help it, nor will it do anything toward solving the largest mass movement of people since World War Two.

The challenge for Europe, then, is to transcend the loud, populist rhetoric of a few self-interested states. It must work with Turkey to cut down on smuggling networks and provide incentives for refugees to remain there under humane circumstances. Otherwise Europe will have another humanitarian crisis on its hands in Greece.