THE glue and the guts of President Bashar Assad's regime are the army and its allies in the police and the Mukhabarat, the intelligence service. So far they have generally stayed loyal. But defectors are growing in number and are getting better organised.

Since the start of the uprising in March there have been defections, mainly from the ranks of Sunni conscripts. Some flee the country, others hide among civilians. In July, Riad al-Asaad, a colonel in his 50s, left for Turkey and announced the formation of the Free Syrian Army. Another group, calling itself the Free Officers' Movement, also emerged.

At the time the two organisations were thin. Defecting soldiers worked in small and disparate groups. But in late September the two outfits announced a merger. They now seem more coherent. The Free Syrian Army says it has 22 “battalions” across the country, with field leaders taking orders from a central command in Turkey. These include the Khalid bin Walid battalion in Homs, where clashes with loyalist forces have been fiercest. In the past few weeks, fighting has also broken out in Idlib, in the north-west, and al-Bukamal, on the border with Iraq.

The role of defectors is changing. “Defected soldiers initially just fled, then they came out with weapons behind protesters just to ensure they were safe to go out,” says a man who received military training and took part in Free Syrian Army actions. Now he says the army defectors are becoming more belligerent, attacking checkpoints, armed pro-regime gangs and military equipment. They often make grandiose claims, for instance to have disabled tens of tanks at a time. These are probably exaggerations. But ambushes of convoys of security men are certainly taking place.

It is not easy to defect. Soldiers are often left in the dark as to where they will be deployed or what they will be expected to do. Only television channels that air state propaganda are allowed in barracks. Soldiers' leave is often cancelled and mobile-phone use is restricted. Military units are mixed; soldiers sleep in dormitories with unknown comrades to stop plans being hatched in groups.

Defecting is dangerous too. It is hard for soldiers to escape unless the borders are close. Defectors who remain in the country are constantly on the move, hiding with families or in rural areas. It is hard to assess defectors' numbers. Colonel Asaad has boasted of some 15,000 from an army that numbers around 220,000. However, the true number is probably a lot smaller.

But defections certainly scare the regime. At the end of September it launched an attack on Rastan, a city close to Homs from where many soldiers hail, after it became a hub for defectors and fell out of government control. Activists also say that Hussein Harmoush, a prominent defector who had fled to Turkey, was kidnapped. He resurfaced in the regime's hands in Damascus, where he made a televised retraction of his previous rebellious statements.