People gather in front of a house after it was hit by a rocket on Jan. 31, in the Reyhanli district in Hatay Province, near Turkey’s border with Syria. A 17-year-old girl was killed in the blast, Turkish officials said, as the country presses its offensive against a Syrian Kurdish militia. (Ozan Kose/AFP/Getty Images)

It is around midday when the day’s third explosion echoes through this small Turkish border town, scattering birds across the sky and bringing the streets to a nervous standstill.

As pedestrians bunch together under storefronts, there is quiet for a moment, and then the ambulances begin to wail.

For Fatma, a Turkish mother of two waiting quietly beside the greengrocer’s, the explosions were starting to feel as familiar as they did ominous. “This is happening every day now,” she said. “I’m just waiting for it all to be over.”

As Turkey presses its long-anticipated offensive against Kurdish fighters across the border in northern Syria, frontier towns like Reyhanli have found themselves along the fault line between the region’s warring rivals. Mortar strikes apparently launched by Kurdish forces are landing daily, setting communities already transformed by ­Syria’s war on edge and hardening support for Turkey’s military operation. 

Syria’s seven-year conflict has provided an opportunity for that country’s Kurdish separatists, known as the People’s Protection Units, or YPG, to establish themselves as a major territorial actor. With U.S. backing, they have captured land the size of Indiana.

Turkey has watched those gains with rising anger, viewing Kurdish consolidation on the ­Syrian side of the border as a national security issue. Ankara has been locked in a decades-old war with the fighters’ Turkish allies, the Kurdistan Workers’ Party, or PKK, and Turkey is framing its nearly three-week-old offensive in the Kurdish enclave of Afrin as a fight against terrorism. 

In Reyhanli and Kilis, another Turkish border town, the streets were unusually quiet this week as residents spoke of anxieties and anger at the cross-border attacks from Syria. Where the midday mortar round landed, a small crowd was not far behind, some cursing the attackers, others wondering whether another round would soon land in the same place.

“That building was a smithy. They’ve taken the blacksmith and the butcher’s son to hospital,” said one man, who declined to give his name as plainclothes policemen watched on. 

“I hope they finish off those terrorists soon. It’s the only way to bring peace around here,” the man said.

Popular support for Turkey’s military operation — code-named Operation Olive Branch — appears widespread, and front pages here are a riot of nationalism. With the organs of the state swinging behind a common message, Turkish President Recep Tayyip Erdogan’s government has shown little tolerance for criticism, arresting hundreds who dared to defy him. 

As Turkish troops and thousands of allied Syrian rebels edge through the mountains surrounding Afrin, cross-border shelling has killed seven people and wounded 113 more across Kilis and Hatay provinces since the operation began, according to ­local media.

A 17-year-old girl, Fatma Avlar, was killed last month as she slept in her sky-blue house on Reyhanli’s southern edge. On the wall of the house, a sign announced her memorial. In the street, mourners gathered, clutching cups of tea, and in the corner alone, an old man sat with his head in his hands and his shoulders shaking.

There are also Syrians among the dead, displaced first from a war zone and now caught in the teeth of a new battle.

In Kilis, the name of 27-year-old Tarek Tabbak, a Syrian refu­gee, is listed on a placard displayed ­outside a 17th-century mosque, which was pierced by a rocket late last month. The name of Muzaffer Aydemir, a 72-year-old Turkish shop owner, appears in the same list. Both are named as “martyrs.”

Turkey hosts more Syrian refugees than any other country, and many have settled in towns and camps along the border. The newcomers have transformed the area, setting up businesses and lining the pockets of enterprising landlords who have turned the influx into opportunity. But their presence has also brought tensions. Turkish residents often view their new neighbors — many of them unable to return home — as a nuisance or a strain on resources.

One Syrian man, for instance, speaking on the condition of anonymity because he feared retribution for public criticism, said his Turkish friends had become angry that their own country’s soldiers had been dragged into the war.

The casualty count among both nationalities is rising. And in ­Afrin, monitoring groups say that dozens of civilians have been killed.

Standing in the doorway of his sweet shop, Fadel al-Masri, a ­Syrian from Aleppo, scanned the street as he described how the attacks had made his son too fearful to sleep. Then nodding curtly to a reporter, he ducked back inside. “Goodbye,” he said. “I don’t want any trouble.”

But next door, Adil Ibanoglo was holding court in his cake shop as the television blared songs and triumphant footage of Turkish tanks rolling through Syria.  “Those bastards will get a shock if they think they can break us. Turkey is a NATO military — those PKK terrorists are going to be smashed,” he said.

Zakaria Zakaria in Reyhanli and Kilis contributed to this report.