Packets of cigarettes and tea gathering dust in his one-room store, Mustafa Karatas doubts a joint US-Turkish plan to flush Islamic State militants from the Syrian border will make much difference to his business any time soon.

This main commercial street in Karkamis, a Turkish town of 10,500 people, sits directly opposite the border post, shut for more than a year. The military sealed the crossing with a breeze block wall a few months ago. Behind it, just inside Syria, the black flag of Islamic State flaps in the breeze.

Karkamis lies on the northeastern edge of a rectangle of Syrian territory some 80km long, controlled by the radical Islamists. The US and Turkey hope that by sweeping Islamic State from this border zone, they can deprive it of a smuggling route which has seen its ranks swollen with foreign fighters and its coffers boosted by illicit trade.

Moderate Syrian rebels, trained by the US army, will fight Islamic State on the ground and help coordinate air strikes by the US coalition, launched from Turkish air bases, under the strategy drawn up by Washington and Ankara.

Diplomats familiar with the plans say cutting off one of Islamic State’s lifelines could be a game-changer in this corner of Syria’s complex war. The core of the rebels, who number less than 60, will be highly equipped and will be able to call in close air support when needed, they say.

But there are major challenges.

They are much better equipped than the rebels currently fighting... You can scatter them around, deploy them in different units

Turkey is distrustful of the Syrian Kurdish YPG militia, which has proved a useful US ally in fighting Islamic State. It controls adjacent territory on the eastern side of the Euphrates river, just across from Karkamis and the jihadist-held town of Jarablus. Ankara wants it to advance no further and considers the Euphrates a red line not to be crossed.

Locals say they hear gun battles at night, but struggle to tell which of the three sides is firing at which other.

The YPG has already accused Turkish tanks of firing on its positions in recent days. Ankara denies targeting the Kurds but has said its forces will defend themselves if attacked.

A Turkish soldier stands guard at the Turkish- Syrian border in Karkamis, bordering with the Islamic State-held Syrian town of Jarablus, in Gaziantep province, Turkey.

A batch of US-trained rebels deployed to northern Syria came under fire on Friday from rival militants, highlighting the threat they face on multiple fronts.

“Of course if they clear Islamic State out it would be great. But I don’t think it will happen any time soon,” said Karatas, 33, sat among plastic toys and kitchen appliances, drawing on a cigarette and doubtful of any quick resolution.

“I have friends and colleagues on the other side who say Isis has placed mines all along the border area and in the town. It will be very difficult to clean up Jarablus,” he said, using one of the acronyms to describe IS.

After years of reluctance, Turkey joined the front-line battle against Islamic State just over a week ago, bombing militant positions in northern Syria and opening its air bases to the US-led coalition after a Turkish soldier was killed in a cross-border exchange of fire.

Ankara has described the strip of land it wants to clear of Islamic State as a ‘safe zone’. President Tayyip Erdogan has said it will pave the way for the return of more than 1.7 million Syrian refugees sheltering in Turkey.

US officials say this is not the prime objective, while the UN has warned against calling it a safe zone unless the protection of civilians can be guaranteed.

So far, there is little sign of Islamic State being dislodged, though diplomats and officials say operations will begin in earnest only once coalition jets arrive in the Incirlik air base in southern Turkey, expected in the coming weeks.

From there, they will be able to strike more rapidly and frequently in northern Syria than from the bases they currently use in the Gulf, and in closer coordination with the US-trained rebels on the ground.

“They are much better equipped than the rebels currently fighting ... You can scatter them around, deploy them in different units. They are like golden tickets, with access to close air support,” said one diplomat familiar with the plans.

In some villages on this stretch of border, little more than razor wire fence separates the fig, hazelnut and olive groves of Turkey from Islamic State-held Syria. Turkish soldiers shelter from the searing sun under sparsely-distributed watchtowers.

Opposite Karkamis, a prominent pink house which villagers say is a local base for Islamic State stands in clear view of Turkish military positions. Around it, men in black balaclavas shore up its defences, digging a trench with an excavator.

“Isis may be a very dangerous group for the world, but they have been here for almost two years,” said Galip Cakir.

The 46-year-old who quit work as a farmer to manage sanitation in a refugee camp near Karkamis says it gave him a more reliable income.

“We’re just watching and waiting,” he said of the US-coalition plans.

“This town used to thrive on cross-border trade. Now, unemployed men gather at a tea-house, playing endless games of cards.”

Karatas once made 3,000 lira (€985) a week in his store, largely from passing truck drivers. Now his takings have all but evaporated and only one other shop on the main street is still open. Even the baker and money changer have left town.

It is a far cry from the days before Syria’s civil war, when the two countries once held joint Cabinet meetings and abolished the need for visas in a bid to deepen trade ties.

“Frankly, I preferred it when the Syrian state was in control,” Karatas said. “The Assad regime was not so bad. Not as bad as what’s here now.”