ISTANBUL >> Turkish tanks have crossed into Syria to the west of a frontier town seized from the Islamic State group last week, in a “new phase” of an operation aimed at sealing off the last stretch of border controlled by the extremists.

The private Dogan news agency reported at least 20 tanks and five armored personnel carriers crossed at the Turkish border town of Elbeyli, across from the Syrian town of al-Rai. The new incursion is unfolding about 55 kilometers (34 miles) west of Jarablus, where Turkish forces first crossed into Syria ten days ago.

The tanks entered from the Turkish border village of Elbeyli and linked up with Turkish-backed Syrian rebels at al-Rai, who are participating in the operation, dubbed Euphrates Shield.

The official Anadolu News Agency said that “with this new phase of the operation, the Azaz-Jarablus line is expected to be cleared of terror elements.”

Turkish-backed Syrian rebels meanwhile said they had captured three more villages to the west of Jarablus from the Islamic State group, bringing them to 13 miles from those positioned at al-Rai. The gap is the last remaining stretch of the Syrian border under IS control.

Three rockets fired from IS-held territory in Syria meanwhile struck the Turkish border town of Kilis, some 19 miles from Elbeyli, according to the Turkish governor’s office, which said one person was lightly wounded.

The governor’s office said five others were wounded last Monday when three rockets hit Kilis. Anadolu said the wounded were children. Dogan says rockets have killed 21 Kilis residents and wounded scores since January.

The Turkish Armed Forces responded to the rockets with howitzers, striking two weapons pits and bunkers, and “destroying the locations and the Daesh terrorists there,” Anadolu said, referring to IS by an Arabic acronym.

Turkey’s military says its right to self-defense as well as U.N. resolutions to combat the IS group justify its Syria incursions.

Turkey and allied Syrian rebels have also fought U.S.-backed Kurdish forces known as the People’s Protection Units, or YPG, around Jarablus. Turkey views the YPG as an extension of the Kurdistan Workers’ Party, or the PKK, which Turkey and its allies consider a terrorist organization.

The U.S. has provided extensive aid and airstrikes to the YPG-led Syria Democratic Forces, which have proven to be highly effective against IS. The Syria Democratic Forces, which also includes Arab fighters, has taking a large swath of territory from the extremists along the border with Turkey and closed in on Raqqa, the de facto capital of the extremist group’s self-styled caliphate.