Kim Sengupta: The Syrian rebels are becoming more viable

Amid the latest rounds of killings and destruction, the further ratcheting up of international tensions and Nato's meeting over the shooting down of a Turkish warplane, a development has taken place which will have a significant impact on the course of Syria's civil war.

A group of 224 middle-ranking military officers and their families have followed two brigadier-generals and two colonels in defecting from the Syrian armed forces. Around 35,000 have fled from Syria into Turkey since the rebellion started last year. But this is the first time that there a steady and growing flow of desertions from forces which have hitherto remained loyal to Bashar al-Assad.

Which side the military takes has been of pivotal importance in the Arab Spring. Large numbers joined the rebels in Libya from the early days of the revolution and it was a decision of the armies in respective countries to withdraw support which led to demise of Hosni Mubarak in Egypt and Ben Ali in Tunisia.

The numbers of ex-servicemen have been rising recently. The public reason given by these men is that they had been forced to fight for the regime and left when they could no longer stand the slaughter of fellow citizens.

This may be true, but Addurrahman Razaq, an artillery sergeant from Maarat al-Numan in Idlib province, went to the hills to join the rebels because of the killings he witnessed but there were other killings after the regime's gunmen left – of those suspected of collaborating by the opposition. Rebels have stepped up the assassinations of soldiers.

And the opposition can now offer better arms. The group I was with on one of my last trips across the border was armed with shotguns and hunting rifles and there was celebration when they got their first Kalashnikov from a soldier for $2,500 (£1,600). Courtesy of money coming in from abroad, the same band now has enough Kalashnikovs to go around.