Ankara: After a predawn barrage of heavy artillery and air strikes, Turkey sent tanks and special forces into Syria on Wednesday to help clear a border town of Daesh militants in Ankara’s most significant military involvement so far in the Syria conflict.

Syrian opposition fighters were also part of the cross-border incursion, which was reported by both Turkish state media and Syrian opposition activists.

Turkey said its intention was to clear the town of Jarablus, located across the border from Turkey, from Daesh militants. But Turkey is also concerned about the growing power of US-backed Syrian Kurdish forces, who it says are linked to Kurdish groups waging an insurgency in southeastern Turkey.

But President Recep Tayyip Erdogan emphasised the operation was also targeting Kurdish militia fighters, opposed by Ankara, who had also been closing in on Jarabulus.

He said the operation was aimed against both Daesh and Democratic Union Party, or PYD — “terror groups that continuously threaten our country in northern Syria.”

“We have said ‘enough is enough’ ... This now needs to be resolved,” said Erdogan.

He added that no one should consider “the Syrian issue to be independent from Turkey’s domestic issues.”

“You will not succeed. You will not divide our nation, you will not lower our flag, you will not tear up our motherland, you will not topple our state,” he said. “You will not silence our calls to prayer, you will not make this country kneel, you will not chain this people.”

The operation — named “Euphrates Shield” — began around 4am local time (0100 GMT) with Turkish artillery pounding dozens of Daesh targets around Jarabulus, the prime minister’s office said.

Foreign Minister Mevlut Cavusoglu said later that Syrian Kurdish fighters must return to the east of the Euphrates river or Turkey will “do what is necessary”.

Cavusoglu, who was speaking in Ankara, also said that no one would be brought in from the outside and settled in the Syrian town of Jarablus,

The spokesman for the Syrian Kurdish YPG militia responded by calling the military intervention a “blatant aggression in Syrian internal affairs” and results from an agreement between Turkey, Iran and Syria’s government.

A senior official with Syria’s largest Kurdish group suggested Turkey will pay the price. Saleh Muslim, the co-president of the PYD, tweeted, “Turkey is in Syrian Quagmire. Will be defeated as Daesh” will be.

Turkey’s state-run Anadolu Agency, citing unnamed military officials, said tanks crossed into Syria but didn’t provide details. The private NTV television said as many as 20 tanks crossed the border and that clashes were under way. Earlier on Wednesday, NTV said a small number of Turkish special forces had crossed into Syria as part of the operation.

NTV described it as an “intruder mission” meant to carry out “pinpoint operations” against Daesh to clear Jarablus of the extremists.

Turkish Prime Minister Binali Yildirim’s office was quoted by Anadolu as saying the operation, carried out by Turkish and US-backed coalition forces, began at 4am (0100 GMT), with Turkish artillery launching intense cross-border fire on Jarablus, followed by Turkish warplanes bombing Daesh targets in the town.

The Syrian Observatory for Human Rights, an opposition activist group that monitors the civil war, said Syrian rebels who were amassed at the Turkish border crossed into Syria, preceded by Turkish tanks and mine sweepers. The Britain-based group didn’t say how many fighters were involved. On Tuesday, it said that around 500 rebels were waiting to cross into Syria.

Turkish state media said rebels made it three-kilometres in the direction of Jarablus. Erdogan said the operation is directed against terror organisations like Daesh and the PYD, the largest Syrian Kurdish group.

Turkish Interior Minister Efkan Ala said the Jarablus operation meant to safeguard Turkey’s security and that Ankara “cannot sit and watch.”

“It is Turkey’s legal right, it is within its authority” to take action, the minister said, adding that Wednesday’s operation was being carried out in coordination with US-led coalition forces.

Turkey’s Hurriyet newspaper quoted Turkish sources as saying Turkish Howitzers and rocket launchers had fired 224 rounds at 63 targets within an hour and 45 minutes, and that the Turkish air raids started just after 6am.

Turkey had declared the border area a “special security zone”, and asked journalists not to try access it, citing safety concerns and threats posed by the Daesh.

On Tuesday, Cavusoglu’s pledged “every kind” of support for operations against Daesh along a 100-kilometre stretch of Syrian frontier. He said Turkey would support twin operations stretching from the Syrian town of Afrin in the northwest, already controlled by Kurdish forces, to Jarablus, in the central north, held by the Daesh group.

Jarablus lies on the western bank of the Euphrates River where it crosses from Turkey into Syria and is one of the last important Daesh-held towns standing between Kurdish-controlled areas in northern Syria. Taking control of Jarablus and the Daesh-held town of Al Bab to the south would be a significant step toward linking border areas under Kurdish control east and west of the Euphrates.

In recent days, Turkey increased security measures on its border with Syria, deploying tanks and armoured personnel carriers. On Tuesday, residents of the Turkish town of Karkamis, across the border from Jarablus, were told to evacuate after three mortars believed to be fired by Daesh militants landed there, Turkey’s Dogan news agency said.

Turkey has vowed to fight Daesh militants at home and to “cleanse” the group from its borders after a weekend suicide bombing at a Kurdish wedding in southern Turkey killed at least 54 people, many of them children. Turkish officials have blamed Daesh for the attack.

Ankara is also concerned about the growing power of US-backed Syrian Kurdish forces, who it says are linked to Kurdish groups waging an insurgency in southeastern Turkey.

The Kurdish-led group known as the Syria Democratic Forces, or SDF, recaptured the town of Manbij from Daesh earlier this month, triggering concerns in Ankara that Kurdish forces would seize the entire border strip with Turkey. The US says it has embedded some 300 special forces with the SDF, and British special forces have also been spotted advising the group.