Pentagon press secretary George Little told reporters the U.S. troops operating the Patriots will be tasked with a defensive mission only. The Patriot surface-to-air missiles could technically be used to enforce a no-fly zone over northern Syria, but NATO officials have stressed that they are not gearing up for such a move, which would mark a sharp escalation in the West’s involvement in Syria’s conflict.

"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," said Little.

Little said the troops would be deployed in the coming weeks once the two Patriot missile batteries are in place but declined to reveal the location.

Panetta issued the order en route to Turkey from Afghanistan, according to the Pentagon.

Panetta told reporters during the trip that the United States and Turkey "share common concerns about the violence in Syria and the threat that it poses to regional stability."