"It is estimated that only about 40 per cent of Syrians oppose Assad..."

"...This is not to say that a NATO-led invasion could not face the Syrian forces and deal them a potentially crushing blow. But it would come with significantly higher costs. Indeed, it is estimated that only about 40 per cent of Syrians oppose the Assad regime. Thus any intervening force would contend, possibly, with 60 per cent of the population viewing such an intervention as an act of aggression. That is, 13.5 million Syrians would oppose the foreign military campaign – twice the number of all Libyans combined.Yet, the crucial difference between the decision to intervene in Libya and merely expressing diplomatic disapproval over Syria is that there is no identifiable rebel group occupying and controlling territory... There is no clear opposition force and protesters do not, under international law, have the status of belligerents – which would make further violence done to them a war crime under the International Criminal Court.
In contrast, Libya’s rebel army was able to gather support and maintain control in the second-largest city of Benghazi, prompting Col. Gadhafi to use air power against the rebels and their supporters. This move by Col. Gadhafi is what ultimately pushed NATO to impose a no-fly zone. Syria’s President has not used air strikes against his own people...
A final note on tactics: Legitimacy is seen as a trump card in any offensive campaign.
In the case of Libya, Col. Gadhafi’s statements, actions and past behaviour generated a very quick response from the international community. Not only did the UN Security Council agree to impose a no-fly zone to protect the rebels, it also voted to recommend a case of possible war crimes and crimes against humanity to The Hague. This dual action of creating a legal mandate and recommending prosecution for violation of international law gave NATO a mantle of legitimacy.
Unlike Libya, Syria can’t gain this same status. Unless Mr. al-Assad commits, with clear evidence, crimes against humanity as defined by the Rome Statutes, the ICC has no hope of jurisdiction. This is due to the fact that Syria is not a signatory to the ICC. The only other available option is for the Security Council to recommend action against the Assad regime. And this is highly unlikely given its performance earlier this month with a failed vote to impose even targeted sanctions on Syria.
Unless Western powers, and not a ragtag group of rebels, are prepared for an on-the-ground invasion, we will continue to merely deplore what the Syrian regime is doing against its people. The principle of responsibility to protect was easily invoked in Libya’s case, but it is not so easily defended in Syria’s. Politics aside, intervening in Syria would be tactically challenging."