As a student a long ago I was like many others a bit infatuated with guerrilla movements in Latin America. Along the way I learned how guerrilla works and it is not nice. It is a strategy of polarization. They start by killing government employees and when the enevitable government reaction happens they are quick to point out any excesses or damages. They see this as a propaganda war where lies are allowed if they help the cause. This cryout over government injustices is supposed to bring them more internal and foreign support.
In any country most people just want to go with their life and initially support for guerrilla's tend to be low as people see them as disturbers of the peace. But as the violence becomes worse the government no longer seems such a good guarantor of peace and support for the guerrilla rises among those who share some of its political goals. If it rises far enough people start to believe that the guerrilla has a genuine chance to win and opportunists start crossing the line too.
A guerrilla has nearly always a civilian counterpart. That counterpart contains both hardcore guerrilla supporters and people genuinely committed to peace. That mix makes it for the regime hard to crack down on it while at the same time it supports the insurrection. Recent "non-violent" strategies like we saw in the color revolutions make a such an opposition an even more powerful tool for a guerrilla.
A guerrilla has to be ruthless with any traitors. But the consequence is that often keep this ruthlessness when they become the new government.
In Syria we see all these strategies back. The armed opposition is ruthless in expanding its influence whenever possible - no matter the price in casualties. That they stayed so long in Baba Amr was no mistake: it was a deliberate strategy to make civilian victims for propaganda purposes. Rebel held territories are not free: many are expelled or killed. And while we still see some opposition members walking freely in Damascus in rebelheld territories such a freedom of opinion is not allowed.
A guerrilla seldomly works without foreign support. Such support provides a base in the initial stage and it provides money to keep going when things are tough. We see this in Syria too. The uprising would have ended long ago under Turkey's previous government.
The Russians know this game better than anyone else as they played it in the past. They know what a bloody game it is and how often it ends in a repressive regime. So they are abhorred that the US - claiming moral superiority - is now playing the same game and supporting guerrilla fighters in Syria and other countries.