NATO has said that it will consider a request from member-state Turkey to deploy Patriot missiles in order to help protect the country's troubled border with Syria.
Anders Fogh Rasmussen, NATO's chief, issued a statement on Wednesday, saying the alliance would discuss the request "without delay".
Turkey's bid for the surface-to-air missiles followed talks with NATO allies about how to boost security on the 900km border with Syria after mortar rounds landed on its territory, increasing concerns about the Syrian civil war spilling over into the country's neighbours.
"Such a deployment would augment Turkey's air defence capabilities to defend the population and territory of Turkey. It would contribute to the de-escalation of the crisis along NATO's south-eastern border," Rasmussen said in the statement.
"NATO is fully committed to deterring against any threats and defending Turkey's territorial integrity."
Diplomatic sources told the AFP news agency that NATO ambassadors meeting later on Wednesday were likely to approve the Turkish request.
Rasmussen said a team would visit Turkey next week to conduct a site-survey for the possible deployment of Patriots.
Ahmet Davutoglu, Turkey's foreign minister, said in Ankara on Tuesday that the Patriot missiles were "a precautionary measure, for defence in particular".
Turkey's border villages have been hit by artillery fire from Syria as forces loyal to President Bashar al-Assad battle rebels trying to oust his regime.
In-depth coverage of escalating violence across Syria
Germany, the Netherlands and the US are the only three NATO members that possess the medium-range missiles.
Guido Westerwelle, Germany's foreign minister, said on Wednesday he had told his ambassador to NATO to approve Turkey's request.
The United States is "favorably disposed" towards Turkey's request to NATO to deploy surface-to-air Patriot missiles on
its border with Syria, a US official said on Wednesday.
"We obviously take the security of our NATO ally, Turkey, very seriously and we would be favorably disposed to this," Mark Toner, a US state department deputy spokesman, said.
"We want to do everything we can to protect our close ally," Toner told journalists.
Earlier, the Dutch government said it would consider Turkey's request.
NATO has deployed Patriot surface-to-air missiles to Turkey twice before, once in 1991 and again in 2003, during both Gulf Wars. Those missiles were provided by the Netherlands.
Turkey has twice this year has invoked Article 4 of the NATO charter which provides for consultations when a member state
feels that its territorial integrity, political independence or security is under threat.
Rasmussen said there was currently no question of imposing a no-fly zone with the back-up of the Patriot missiles.