NATO chief Anders Fogh Rasmussen has warned Syria not to use its stockpile of chemical weapons.
He said the Assad regime would face serious consequences if any such arms were used by its forces.
“The possible use of chemical weapons would be completely unacceptable for the whole international community. And if anybody resorts to these terrible weapons, I would expect an expect an immediate reaction from the international community,” Rasmussen said.
NATO foreign ministers meeting in Brussels also approved the deployment of Patriot anti-missile batteries to Turkey.
Ankara wants the missiles to defend itself against possible attacks from inside Syria.
Georges Chachan of the opposition Syrian National Council said: “It was understandable that Turkey wanted to protect its territory and its people from attacks by the regime.”
He said Assad’s government was “entering a desperate phase after the opposition’s siege of Damascus”.
NATO says the missiles will be used for self-defence only, and they are not to be used in attacks on Syrian aircraft.