NATO foreign ministers have agreed to the deployment of Patriot anti -missile batteries on Turkey's border with Syria.
The move had been expected amid growing fears that Syria could use chemical weapons, the BBC reports.
Syria has insisted it will not use chemical weapons against its own people, "in any circumstances".
The meeting of the 28-member Western military alliance's foreign ministers in Brussels follows a request from Turkey to boost its defences along the border.
A NATO team has already visited a number of sites in Turkey in preparation for the deployment of Patriot batteries, which could be used to shoot down any Syrian missiles or warplanes that stray over the border.
Analysts say any deployment - possibly supplied by the US, Germany or the Netherlands - could take weeks.
The CIA believes Syria has had a chemical weapons programme for years and that it has a stockpile of chemical weapons which can be delivered by aircraft, ballistic missile, and artillery rockets"