If we hadn't backed the rebels or demanded Assad leave at all, the left would currently be on their high horse about how we keep kowtowing to dictators and don't do enough to support moderate, democratic movements in the Middle East.

Want to know how you can seem good about the Middle East?

When the dictator is evil and in power, you claim that you want them to be replaced by a liberal democracy. This is exceptionally easy, and anyone who questions whether it is possible is a racist for opposing democracy.

When there is a revolution you stand back and say that we shouldn't get involved because all western involvement is bad and this is the opportunity for a new start. You get to do nothing while seeming nice and attacking imperialists for wanting to help.

When the revolution falters and it looks like it might need help, you claim that it is too early to tell and suggest holding off until all other options are exhausted. The UN is wonderful for this, by claiming you want international legitimacy you can outsource morality to Russia and China to justify your own unwillingness to act. Alternatively if confronted with a strong argument that action must be taken, you can just assert that other Arab States should do it, with full knowledge that is about as likely as the Dictator finding Jesus, giving up of his own free will and accepting an international trial.

This tends to lead to a quagmire and stalemate. This is really good, because war has a transformative effect on oppositions, empowering the more militant and effective parts of it while harming the liberal, democratic side. Then, when you want to seem like a peacemaker, you can say 'well, some form of deal should be done to ensure peace'. When the rebels don't want to do a deal, because a deal means the dictator and his regime remaining in a strong position to destroy and purge them at a later date and none of their demands, you get to call them extremists, then do what people are doing now with Assad. Lesser of two evils, importance of stability, all that jazz. When he wins, 5 years down the line, just move back to stage 1.

Simple. All it takes is careful positioning, and you get to sit on your moral high horse and at every stage you can hide behind an idealistic facade to justify doing absolutely nothing while millions of people die.

Then, a few years after doing nothing but being difficult, you can discover that refugees exist, and start demanding we help them while claiming the moral high ground over the person who has spent a billion quid helping them before it was cool.