"I would expect that the Syrian authorities will do all they can to avoid any escalation and any such unacceptable incident as we saw when they shot down a Turkish aircraft," Rasmussen told a joint news conference with Slovenian Prime Minister Janez Jansa in Ljubljana.

"It goes without saying that Turkey can count on NATO. NATO is of course prepared to defend Turkey if it is so necessary," he added.

A Turkish F-4 Phantom was shot down on June 22 by Syrian fire but the two countries disagree on whether the incident took place in international or Syrian airspace.

After the incident, Turkey requested consultations under Article 4 of NATO's founding treaty, enabling any of the allies to call for talks should they consider their territorial integrity, political independence or security to be under threat.

"We all agree that there is no military solution to the crisis in Syria, we need a political solution," Rasmussen also said during his one-day visit to Slovenia.

A weekend deal by world powers in Geneva aimed at achieving a transition of power in Syria was "a step in the right direction," he said.