The Syrian regime has fired Scud-type missiles against rebel forces in what NATO chief Anders Fogh Rasmussen on Friday said was an act of desperation.
"I can confirm that we have detected the launch of Scud-type missiles; we strongly regret that act," Rasmussen said, adding: "I consider it an act of a desperate regime approaching collapse."
The latest launches were detected on Thursday, a source close to NATO said.
The use of such missiles by President Basahar al-Assad's regime also highlights the "need for effective defence and protection of our ally Turkey," Rasmussen said, referring to the planned deployment of Patriot anti-missile batteries along its southern border with Syria.
Rasmussen stressed that the missiles had not landed on Turkish territory but they nonetheless posed a potential threat which had to be countered.
The Patriot deployment, to be made by NATO allies the United States, Germany and the Netherlands, is for a "defensive purpose only," he said.
The mobile medium-range Scud, is a Soviet-era missile which can carry a warhead of up to 1,000 kilograms (2,200 pounds). The missiles can be equipped with conventional, chemical or nuclear warheads.