NATO has assembled for a special session after Syria shot down a Turkish war plane which it said had gone into Syrian airspace. This follows the letter Turkey sent to the UN Security Council, which described the incident as a "hostile act by the Syrian authorities against Turkey's national security.

A Syrian foreign ministry official speaking at a press conference said his country has reacted in a defensive and sovereign way to the Turkish war jet which entered Syrian airspace on Friday, adding that the breach is an encroachment upon the country's sovereignty. This is what he had to say.

Over in Turkey a Middle Eastern expert said Syria wants to show they are a force to be reckoned with. Speaking in Turkish this is what he said.

"In my opinion, Syria wants to send a clear message to Turkey that the Syrian government is strong and it is impossible for any external forces to subvert the regime."

This is the latest downturn in the previously good Syrian-Turkish relations, which have hit rock bottom since unrest in Syria began last year. The two sides had been close allies before the Turkish government turned against the government of Bashar al-Assad.

Turkey has opened its borders to harbour Syrian refugees who have allegedly escaped the violence in their hometowns. Meanwhile, Syria has also accused their northern neighbour of harbouring armed elements and army defectors.

Written and Presented by Ann Salter