A Pentagon spokesman said Friday Defense Secretary Leon Panetta signed the order while he was traveling to Turkey to visit Incirlik Air Base, CNN reported.
Spokesman George Little declined to say where the batteries would be placed nor how long the troops would be deployed.
"The purpose of this deployment is to signal very strongly that the United States, working closely with our NATO allies, is going to support the defense of Turkey, especially with potential threats emanating from Syria," he said.
Six Patriot missile batteries will be sent to Turkey -- two each from the United States, Germany and the Netherlands, Today's Zaman reported. The batteries will be under NATO's command and are expected to be operational by the end of January.
Turkey asked NATO to deploy Patriot missiles to protect its border with Syria, engulfed in a civil war between rebels and President Bashar Assad. The fighting, which began in March 2011, has resulted in increased clashes along the countries' shared border.
Turkey, a NATO member, supports the rebels and is home to many thousands of Syrians who fled the violence.
The military alliance's ministers have said the deployment would be for defensive purposes only.