ONCUPINAR, Turkey (Reuters) – As the number of Syrian refugees now amassing on the Turkish border swells into the tens of thousands, Ankara’s long-standing open door to migrants may be closing.

An assault by Russian-backed Syrian government forces around the city of Aleppo has sent more than 30,000 people fleeing to the Turkish border gate of Oncupinar in the past few days, and officials say tens of thousands more could be on the move.

The surge has created a bitter irony for Turkey.

Praised on the one hand for taking in more than 2.5 million refugees from Syria’s five-year war, it is also under pressure to stop their perilous onward journeys to Europe, and to prevent radical militants from sneaking over what was long a porous border to carry out attacks in Turkey or abroad.

Yet as it tries to keep the gates shut at Oncupinar and provide aid across the border instead, it now finds itself facing calls to let people in.

“We have much wider considerations now … There are terrorist organizations that weren’t there when the Syrian conflict first began,” a senior government official who deals with immigration issues said, explaining how the situation on the border had changed in recent years.

A growing number of refugees just wanted to use Turkey as a staging post to Europe despite the dangers, he said, leaving Ankara with a responsibility to stop incidents like the drowning of a Syrian toddler last September as his family tried to reach the Greek islands, an image which stirred worldwide sympathy.

“Let everyone in and you may see another Aylan Kurdi.”

Turkish aid groups are delivering food and supplies to tent villages on the Syrian side of the border at Oncupinar and the local authorities say there is no need, for now, to open the gates. President Tayyip Erdogan has said that, if necessary, the refugees will ultimately be allowed in.

Ankara has long argued that the only sustainable way to manage the migrant flow is to establish a “safe zone” inside Syria, an internationally protected area where displaced civilians can be given refuge without crossing into Turkey.

The idea has gained little traction with Western leaders, who see battling Islamic State in Syria as the main priority and fear protecting such a zone would put them in direct military confrontation with President Bashar al-Assad’s forces.

But on a small scale, Turkey is putting it into practice at Oncupinar.

A wounded teenager and his father were let through by foot early on Monday, while a trickle of ambulances ferried the badly injured to hospitals in nearby Turkish towns. But for the majority, the border is firmly closed.

“Unless their lives are in danger, unless there’s an imminent risk, the arrangements on the Syrian side have the capacity to accommodate them,” the government official said.

WAITING TO ENTER TURKEY

In the camps at Bab al-Salama on the Syrian side, where children play in muddy lanes between rows of tents lashed by rain, some are starting to wonder whether they are still welcome in a country they once saw as a guaranteed safe haven.

“I have been here for the past month. I am waiting for Turkey to open the door,” said Dilel Cumali, a woman who fled from Dera’a in Syria’s southwest near the Jordanian border.

“There are no beds, no food, nothing to wear. We had to sleep where it’s wet and there’s nothing to cover ourselves with. There is nothing to feed the kids. We don’t want anything. All we want is to get inside Turkey.”

Under a November deal with the European Union, Turkey agreed to do more to integrate its refugee population – now the world’s largest – and try to lower the number of asylum seekers arriving in Europe after over a million streamed onto the continent in 2015, many by sea from Turkey.

At least 22 migrants drowned after their boat capsized in the Aegean sea off the Turkish coast on Monday, suggesting the exodus shows no sign of abating.

Asked on Saturday about the migrants at Oncupinar, EU foreign policy chief Federica Mogherini said Turkey had a moral and legal duty to protect refugees, adding EU support to Ankara was aimed at guaranteeing it could cope with them.

FRUSTRATION

Turkey, a NATO member with a 560-mile border with Syria, is increasingly frustrated at the international failure to do more to stop the bombing by President Bashar al-Assad’s forces and his allies including Russia, which it sees as the root cause of the migrant flows.

“Those who can’t say stop the bombardment are saying stop the immigration wave. If you’re serious, stop the authors of that cruelty,” said Deputy Prime Minister Yalcin Akdogan, a long-standing Erdogan advisor.

A suicide bombing in Istanbul last month which killed 10 German tourists, carried out by a Saudi-born Syrian who entered Turkey as a refugee, served only to highlight the risks.

Around Oncupinar, eight camps were set up on the Syrian side for some 60,000 people even before the latest influx, according to Oncupinar governor Suleyman Tapsiz. A ninth is being built.

“There is a perception that Turkey has shut its doors and is not doing anything. On the contrary, there are major efforts to accommodate these people on the Syrian side,” a second Turkish government official said.

“It’s not like we’re shutting our doors in their face.”

A flag of the opposition Free Syrian Army fluttered over the road that leads out from a camp at Bab al-Salama to the Syrian city of Azaz, one of the last towns between the Syrian army’s advance and the Turkish border. Opposition fighters holding Kalashnikovs milled around nearby.

“I fled Assad’s and Russia’s bombardment. Please tell them to open the doors so we can move to safety. We have no safety here,” said Sabah al-Muhammed, an elderly woman who said she had walked for 10 hours to reach the border.

Even amid the chaos of Syria’s war, the message that Europe’s borders were closed had reached her.

“I swear to god, we don’t want to go to Europe, we don’t want Europe. We are Muslim people and we want to live in a Muslim country,” she said.

(Writing by Nick Tattersall; Editing by David Dolan and Philippa Fletcher)