Syrian President Bashar al-Assad has earned more enemies than he can possibly handle during a crisis. His forces now face twin attacks, from the fighting opposition groups and Syria's neighbour Turkey.

Days after the Syrian mortar attack on Turkish civilians, Istanbul is hitting back strongly. Turkey has been returning fire for a third consecutive day as Assad's forces have persisted with shelling.

Turkish state media said the country responded with fire as Syria shelled the border region, but no casualties have been reported so far.

A day after the Turkish parliament authorised its military for cross-border operations, Prime Minister Tayyip Erdogan issued a stern warning: "We are not interested in war, but we're not far from war either. This nation has come to where it is today having gone through intercontinental wars. Those who attempt to test Turkey's deterrence, its decisiveness, its capacity, I say here they are making a fatal mistake."

The US government also expressed support for Turkey and condemned Syria's actions.

On another front, Assad's forces are engaged in trying to quell rebel attacks which have intensified in recent days.

Assad's troops continued with airstrikes and artillery attacks. Homs province experienced heavy shelling where scores of people have been reported killed. Explosions and gunfire were also reported by nearby residents.

The neighbourhoods of Damascus and other parts of Syria have been witnessing deadly armed confrontations. A Syrian warplane has also reportedly been brought down by the rebels.

Anti-Assad activists say the lightly-armed rebels had taken down an aircraft in al-Ghouta region, one of the suburbs of Damascus. An unconfirmed video has also been uploaded online showing a truck collecting wreckage, which the activists claim, is that of the warplane.

Some pro-regime reports also confirmed that the jet was brought down although no official word has been put out. The rebels do not have heavy weapons, but they continue to claim attacks on Assad's warplanes and helicopters.