SENTILJ, Slovenia —With Slovenia behind them and Austria just ahead, the asylum-seekers shoved at the metal barriers blocking their path and chanted a plea into the smoky night air: “We want to go!”

Nearly 1,000 people had been waiting all day for the border crossing to open, penned into a no-man’s land by twitchy troops armed with pistols and assault rifles who met requests for food or water with stern commands and glares icy enough to match the fast-falling temperature.

Migrants wait in Slovenia to gain entrance to Austria. Officials in Austria say that if Germany closes its borders, Austria may be forced to do so, too. The Associated Press

Migrants and refugees wait outside the Moria camp on the Greek island of Lesbos in October. Congress and many governors are putting pressure on the Obama administration to demonstrate that its screening process for refugees is adequate to protect Americans. 2015 Associated Press file photo

“We’ve already spent two nights outside,” said Galia Ali, pointing to her severely disabled 8-year-old son, who lay shivering on a blanket near a dwindling fire. “If we’re still here in the morning, he’ll be dead.”

Hours later, the barriers were lifted, and the migrants surged into Austria. But up and down the route being traveled by a historic number of migrants this year as they seek new lives in Europe, pressure is building to close the continent’s cherished open borders for good.

Hungary already has proved that it can largely insulate itself from the refugee crisis by deploying razor wire and threatening lengthy prison sentences for anyone who dares cross it. The country’s moves have shifted the burden of the refugee crisis to its neighbors – and are now tempting leaders in those nations to build their own fences.

FEAR OF DOMINO EFFECT, CHAOS

The U.N. refugee agency said Monday that a record 218,394 people crossed the Mediterranean to reach European shores in October – about as many as the total from all of last year. As the numbers rise, officials in countries across central and southeastern Europe are eyeing one another nervously, fearing that a sudden closure of any one border could unleash a domino effect across the region that would leave tens of thousands of people stranded and angry, far from their intended destinations in the continent’s north.

The result would be chaos and violence, said Croatian Interior Minister Ranko Ostojic, who has coordinated his country’s response as more than 300,000 people have crossed through the small coastal nation since mid-September – including 8,400 on Sunday alone.

“You really think you can stop these people without shooting?” Ostojic said. “You’d have to build a wall around Europe if you really wanted to stop these kinds of flows.”

Rather than try to impede the movement of migrants, Croatia has sought to speed it up, arranging trains to ferry people from the Serbian border in the east to the Slovenian border in the west. But the country’s right-wing opposition, which is a slight favorite to win national elections Sunday, has proposed a different solution: a fence.

Slovenia has said it is considering a fence of its own. Foreign Minister Karl Erjavec described that action as “a last resort” but added that he is “very much concerned” that other countries will erect barriers, leaving his tiny Alpine nation shouldering an unsustainable burden. Even now, he said, Slovenia is struggling to cope.

“We cannot go on like this for a long time,” Erjavec said in an e-mailed response to questions. “We have received more than 100,000 migrants in just two weeks. This number represents 5% of our population. Our human, financial and material resources are limited.”

WHEN GERMANY HAS ‘HAD ENOUGH’

Farther up the trail, Austrian officials said last week that they are planning barriers to better regulate the movement of migrants coming across from Slovenia. They quickly clarified that they have no intention of closing the border. But they also have said they will not be able to leave it open if Germany – the next stop after Austria and for many asylum seekers the final destination – decides it can no longer handle an influx that brought more than a half-million asylum seekers to the country during the first nine months of the year. As her poll numbers fall, calls are growing for Chancellor Angela Merkel to do exactly that.

“Everyone is afraid of the moment when Germany decides it has had enough,” said Igor Tabak, a Croatian security analyst for the Web site Obris.org.

The closure of borders, Tabak said, would not only undermine the principle of free movement at the heart of Europe’s post-Cold War identity, but it also could be deeply destabilizing in the Balkans, where countries that were in conflict with one another less than a generation ago are being forced to cooperate on the biggest challenge to confront the European Union in decades.

Slovenia, Croatia and Serbia have spent weeks trading accusations of mishandling the crisis. Should a right-wing Croatian government opt to close the border with Serbia, Tabak said, the flow would probably shift to Bosnia, an ethnically divided nation that has struggled to hang together since its blood-soaked birth.

“If you have an influx of a large number of migrants into such a fragile system, it’s easy to imagine the local institutions crumbling in Bosnia,” Tabak said.

Ostojic, the Croatian interior minister, said coordination among the regional rivals has improved after an emergency meeting of Balkan nations in Brussels late last month. In recent days, trains have begun to speed migrants through the region as part of a trial program that is expected to be fully rolled out this week.

SLOVENIA WAS ‘NOT PREPARED’

The system replaces one that officials acknowledge was woefully unsuited to the scale of the crisis. In the first two weeks after Hungary closed its border with Croatia, forcing migrants to reroute through Slovenia, thousands of people slept in the open each night as rain poured and temperatures plummeted.

Slovenia accused Croatia of sending migrants streaming across the border without warning. Croatia charged that Slovenia had failed to ready itself – a point that some Slovenian officials now concede.

“Nobody had foreseen what was going to happen. The country was not prepared,” said Ivan Molan, mayor of Brezice, a handsome Slovenian town of red-tiled roofs and quiet lanes that has borne the brunt of the crisis.

Molan said the new system of moving asylum seekers across borders by train could help to normalize life in a place where up to 10,000 people had been trekking each day through farmers’ fields and driving away the tourists who normally flock to Brezice for a dip at its thermal spas.

But he fears that the Austrians will close their border, trapping frustrated migrants in Slovenia. The country, like others in the Balkans, has no recent history of welcoming refugees from outside the region and has little to offer them. “If that happens, this part of Slovenia will descend into a real crisis,” Molan said.

At the other end of the country refugees who were awaiting the chance to walk into Austria said they were desperate to leave a place that had brought them only grief.

“I didn’t even know Slovenia existed before I came here,” said Sozdar el-Hassan, a 24-year-old from Damascus who stood pressed against an iron barricade while clutching her 22-month-old daughter. “It’s the smallest country, but it gave us the most problems.”

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