A Turkish official on Thursday described the movement as a precaution after Syrian air defenses shot down a Turkish warplane a week ago.

US Defense Secretary Leon Panetta noted that Turkey has maintained troops along the border.

"And I wouldn't read too much into the movements that have been in the press," Panetta told reporters at the Pentagon.

Army General Martin Dempsey, chairman of the US military's Joint Chiefs of Staff, added that "I wouldn't read that as provocative in any way."

Dempsey, who recently spoke with his Turkish counterpart, General Necdet Ozel, added: "You'd probably have to ask the Turks. I've asked them and they are not seeking to be provocative."

Commenting on his conversation with Ozel, Dempsey said: "He's taking a very measured approach to the incident. So he and I are staying in contact."

Turkish commanders on Friday inspected missile batteries deployed in the border region, seen as a graphic warning to Assad after last Friday's shoot-down of the Turkish plane.

Regional analysts said that while neither Turkey nor its NATO allies appeared to have any appetite to enforce a formal no-fly zone over Syrian territory, Turkish Prime Minister Tayyip Erdogan had made it clear Assad would be risking what he called the 'wrath' of Turkey if its aircraft strayed close to its borders.

Erdogan told a rally in the eastern city of Erzurum on Friday, broadcast by Turkish television: "We will not hesitate to teach a lesson to those who aim heavy weapons at their own people and at neighboring countries."

The Turkish border region is sheltering more than 33,000 Syrian refugees as well as elements of the rebel Free Syrian Army.