Turkey has been careful to make clear it plans no offensive action and does not want a war with Syria, which shares a more than 500-mile border.

Turkish President Abdullah Gul told reporters November 8 that while going to war with Syria was "out of the question," precautions were needed against "ballistic missiles as well as mid-range and near-range missiles."

The U.S.-made Patriot missile system -- which became well known during the first Gulf War in the early 1990s when it protected American allies against Iraqi Scud missiles -- works well against short- and medium-range missiles.

Last month, Syrian artillery shells hit the Turkish border town of Akcakale, killing five Turkish citizens. Soon after, the Turkish Parliament approved a resolution that would allow the military to carry out cross-border incursions.

Since then, Turkish forces have retaliated swiftly with artillery after more than a dozen cross-border artillery strikes believed to have been carried out by the Syrian military.

Once-cozy relations between Syria and Turkey have all but collapsed since the Syrian uprising began last year. Turkey is officially hosting more than 111,000 Syrian refugees, but the Turkish government says tens of thousands of unofficial refugees also live in Turkish cities and towns near the Syrian border.

Meanwhile, Damascus has repeatedly accused its former ally of meddling in internal Syrian affairs by funding and arming the Syrian opposition, as well as providing sanctuary and medical care to Syrian rebels.