After several years of floundering over the Syrian refugee crisis, Lebanon’s fractious political leadership has heeded public outcry to stem a flow that has brought 1.5 million war-displaced people across its border. Under restrictions that took effect Monday, Syrians fleeing their country’s civil strife will no longer be guaranteed free passage to Lebanon without a valid visa, cancelling an open-door policy for its neighbor that had been in place since 1943.

The policy shift was a long time in the making for Lebanon, where fears have simmered that another permanent refugee crisis in the mold of the 1948 Palestinian exodus could be in store. More than 400,000 Palestinians — refugees and their descendants — still live in decrepit United Nations-run camps across the country, almost seven decades after being driven out of homes in what is now Israel.

In recent months, Lebanon has begun to buckle under the added weight of its Syrian guests, who constitute nearly 1 in 4 people living in the country today. The sheer number of refugees has grated on host communities, as Syrians take low-paying jobs, crowd cities, and overburden Lebanon's severely deficient water and power infrastructure. Meanwhile, violent spillover from the Syrian war and reports that desperate Syrians are signing on with extremist factions like Al-Qaeda and the Islamic State in Iraq and the Levant (ISIL) have transformed the perception of refugees in Lebanon “from victims into potential threats,” said Lina Khatib, director of the Carnegie Middle East Center in Beirut. “It became such that the government couldn’t afford to ignore it anymore.”

Lebanon is just the latest host country to protest its refugee burden, which has swelled as international aid dwindles. Jordan has increasingly shuttered its northern border with Syria, trapping swarms of would-be refugees in a war zone, and recently cut off health services to the roughly 700,000 Syrians already sheltered in its towns and cities. Similar bottlenecks have occurred along Syria’s border with Turkey.

Regional governments look to Jordan, a majority Palestinian “refugee nation,” where U.N.-administered camps have long since grown into permanent neighborhoods of Amman or even standalone cities. With the Syrian war growing more complex with the ascension of ISIL, fears in Lebanon have swelled.

That, in part, is why Lebanon has declined to classify Syrians fleeing the war as “refugees,” preferring to call them naziheen — “displaced persons.” Deprived of formal refugee camps, Syrians in Lebanon often take shelter in abandoned buildings or makeshift encampments that provide little protection against the elements.

But Lebanon’s most pervasive anxieties harken back to the country’s civil war, which took place in the backdrop of the militarization of disgruntled Palestinians in Lebanese refugee camps, which became the target of Israeli raids and eventually a full-blown invasion. The armed Palestinian factions also helped fuel the sectarian civil war between Maronite Christian, Shia and Sunni Muslim factions in which 20,000 people died between 1975 and 1990, before an ever-fragile peace accord patched over the fault lines.

Those volatile divides have deepened as a result of its neighbor's war, with the influential Lebanese Shia group Hezbollah sending militias to fight on the side of President Bashar al-Assad. Shias and many Christians in Lebanon worry that Sunnis, who mostly oppose Assad, could exploit the influx of more than a million Sunni Syrians to disrupt the country’s delicate sectarian balance.

Northern Lebanon has seen a steady rumble of spillover violence, punctuated by errant shelling, kidnappings and gun battles that have killed dozens of Lebanese soldiers. Reports of rising Syrian support for extremist groups like ISIL have spurred Lebanese citizens to grow ever hostile, in some case imposing vigilante curfews on Syrians living in their neighborhoods.

In the wake of this week's policy shift, some analysts say Lebanon has fallen victim to paranoia. Dawn Chatty, the former director of Oxford University’s Refugee Studies Center and the author of several books on refugees in the Middle East, rejected the notion that Syrians were being used as pawns in the Lebanese political system. “They’re not voting, they really have no impact in Lebanese politics,” she said. “You heard the same type of fear mongering in the 70s, but even then the civil war was really more about the impoverished Lebanese masses.”

Chatty noted that the new restrictions, which will still allow Syrians with medical, work and landowner visas to cross, could be logistically difficult to enforce. Government officials also underlined that there would still be humanitarian exceptions to the rules for Syria's most vulnerable, though they did not elaborate.

In any case, observers say the pronounced region-wide shift towards a hardline policy on Syria’s refugees may backfire. Compounding the hardship of desperate Syrians, who work mostly as informal day laborers with limited access to education, is more likely than not to exacerbate tensions within host communities. “This is no way to deal with the problem, and if anything makes Syrians more likely to embrace extremist groups,” said Khatib, of the Carnegie Center.

Instead, she urged better coordination between central and local governments, with a view to stem the flow of aid money into the pockets of corrupt politicians — money meant for refugees and their host communities. International aid will also need to overcome so-called donor fatigue and replenish UN coffers.

But while the outlook for ending Syria’s war remains bleak, comparisons to the Palestinian crisis are premature, said Chatty, who just returned from several weeks in Lebanon. “For Palestinians, their country disappeared — they became stateless for eternity. For Syrians, there is still a strong hope for return,” she said.