NATO Secretary-General Anders Fogh Rasmussen said in a Twitter post that the request would be considered without delay. A fact-finding team is on the ground in Turkey, according to Lt. Col. Jay Janzen, a spokesman for Supreme Headquarters Allied Powers Europe.

"The fact-finding teams include experts from the nations that have shown their willingness to offer Patriots as well as Turkish officials and a few NATO experts," he said.

Turkish officials have emphasized that any deployment of the Patriot missiles would be purely for defensive measures. President Abdullah Gul said earlier this month that Turkey has no intention of going to war with Syria.

A NATO official who is not authorized to speak on record to the media told CNN that the fact-finding team now in Turkey includes military personnel from Germany, the United States and Holland, the three countries that have available Patriot missile batteries.

The official also indicated that those batteries could be deployed dozens of kilometers away from the border fence.

"No decisions have been made about the location and numbers of Patriot batteries in Turkey," the official said.

The official said he doesn't believe "there will be an imminent threat from this deployment escalating the conflict between Turkey and Syria."

"By contrast, I think it will demonstrate a deterrence effect," the official said, "and make it clear that NATO is prepared to defend Turkish territory and Turkish population."