NATO must review its ability to fend off threats to the alliance from Syria, including the possible use of chemical weapons, US Secretary of State John Kerry said Tuesday.
"We should ... carefully and collectively consider how NATO is prepared to respond to protect its members from a Syrian threat, including any potential chemical weapons threat," Kerry told a meeting of NATO foreign ministers.
NATO had "demonstrated its resolve and solidarity" by deploying Patriot anti-missile batteries along member Turkey's border with Syria to prevent any spillover of the fighting, Kerry noted.
"Moving forward, we need to continue to consider NATO's role as it relates to the Syrian crisis.
"Planning regarding Syria ... is an appropriate undertaking for the alliance," he added.
The United States has said the use of chemical weapons by President Bashar al-Assad would cross a red line, completely changing the stakes in the bloody conflict.
Israeli officials said Tuesday they had evidence Assad's forces had used chemical weapons, probably the nerve gas sarin, against the rebels.
But Washington has declined to be drawn on the issue, saying it is still studying evidence.
NATO head Anders Fogh Rasmussen echoed Kerry's remarks.
"I can assure you that we stand ready to defend, protect our allies, in this case Turkey," Rasmussen said.
He said he was "extremely concerned about the use of ballistic missiles in Syria and the possible use of chemical weapons."
While NATO has no direct role in the conflict, apart from protecting member states including Turkey, it "could affect our own security and we will remain very vigilant," he added.
The worsening conflict in Syria and the potential for it to spread to the region was a major talking point at the foreign ministers' meeting.