ANKARA, Turkey (AP) — Turkey's military launched an operation before dawn Wednesday to clear a Syrian border town from Islamic State militants, and a private Turkish TV station reported that a small number of Turkish special forces had crossed into Syria as part of the operation.

Turkish government officials could not immediately confirm the report of the cross-border incursion.

The office of Turkish Prime Minister Binali Yildirim said the operation, carried out by Turkish and U.S.-backed coalition forces, began at 4 a.m. (0100 GMT), with Turkish artillery launching intense cross-border fire on the town of Jarablus, followed by Turkish warplanes bombing IS targets in the town, the state-run Anadolu Agency reported.

Just a few hours after the operation started, Vice President Joe Biden landed in Ankara for talks that include developments in Syria.

The visit comes at a difficult time for ties between the two NATO allies. Turkey is demanding that Washington quickly extradite a U.S.-based cleric blamed for orchestrating last month's failed coup. The United States is asking for evidence against the cleric and asking that Turkey allow the extradition process to take its course.

In Syria, Turkey is concerned about the growing power of U.S.-backed Syrian Kurdish forces, who it says are linked to Kurdish groups waging an insurgency in southeastern Turkey. Wednesday's operation puts Turkey on track for a confrontation with the Kurdish fighters in Syria.

Biden is scheduled to meet with Turkish President Recep Tayyip Erdogan and Prime Minister Binali Yildirim.

The operation in Jarablus is meant to safeguard Turkey's own security, according to Turkish Interior Minister Efkan Ala, who said 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 aimed to support the moderate Syrian opposition and was being carried out in coordination with the U.S.-led coalition forces.

Turkey's Hurriyet newspaper, citing unnamed military sources, said a ground offensive in Syria had not yet started but that efforts were underway to open a "passage" into the region. It 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 6 a.m.

The private NTV television said Turkish special forces entered Syria in what it described was an "intruder mission" to carry out "pinpoint operations" against IS as part of the mission to clear the town of Jarablus of the extremists.

The London-based Syrian Observatory for Human Rights also said Turkish ground troops had entered Syria. The activist group, which tracks the war through a network of local residents and fighters, said Turkish tanks and anti-mine vehicles crossed into Syria and were heading to Jarablus on Wednesday morning.

The Turkish government said the border a rea had been declared a "special security zone," and asked journalists not to try access it, citing safety concerns and threats posed by the IS.

The assault followed Turkish Foreign Minister Mevlet Cavusoglu's pledge on Tuesday of "every kind" of support for operations against IS along a 100-kilometer (62-mile) stretch of Syrian frontier. He said Turkey would support twin operations stretching from the Syrian town of Afrin in the northwest, which is already controlled by Kurdish forces, to Jarablus, in the central north, which is held by the Islamic State group.

Jarablus, which lies on the western bank of the Euphrates River where it crosses from Turkey into Syria, is one of the last important IS-held towns standing between Kurdish-controlled areas in northern Syria.

Located 20 miles (33 kilometers) from the town of Manbij, which was liberated from IS by Kurdish-led forces earlier this month, taking control of Jarablus and the IS-held town of al-Bab to the south would be a significant step toward linking up border areas under Kurdish control east and west of the Euphrates River.

In recent days Turkey has increased security measures on its border with Syria, deploying tanks and armored 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 IS militants landed there, Turkey's Dogan news agency said.

Turkey has vowed to fight IS 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 IS for the attack.

Ankara is also concerned about the growing power of U.S.-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 Manbij from IS earlier this month, triggering concerns in Ankara that Kurdish forces would seize the entire border strip with Turkey. The U.S. says it has embedded some 300 special forces with the SDF, and British special forces have also been spotted advising the group.

The Kurds' outsized role in the Syrian civil war is a source of concern for the Syrian government as well. Fierce clashes erupted between the two sides over control of the northeastern province of Hasakeh last week, and Syrian warplanes bombed Kurdish positions for the first time, prompting the U.S. to scramble its jets to protect American troops in the area.

The Syrian government and the Kurds agreed on a cease-fire Tuesday, six days after the clashes erupted. The Kurdish Hawar News Agency said government forces agreed to withdraw from Hasakeh as part of the truce.

Syrian state media did not mention any withdrawal, saying only that the two sides had agreed to evacuate the wounded and exchange detainees. Government and Kurdish forces have shared control of Hasakeh since the early years of the Syrian war.

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Issa reported from Beirut.

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This story has been corrected to fix the misspelling of Turkish foreign minister's last name, to Cavusoglu.