The politics for a safe zone have been discussed in the Economist newspaper (which is very well connected on both sides of the Atlantic) for some months. As in this article from last November.
Middle East and Africa: Syria?s agony | The Economist
The idea was promoted publicly in America by Senator John McCain the week before last:
PressTV - McCain urges 'safe zone' for Syria rebels
The debate on this has hotted up considerably over the last couple of days since the Israeli strikes:
Democrats and Republicans think US closer to arming Syrian rebels, after Israeli strikes | Fox News
America just recently put a lot of diplomatic effort in getting Turkey and Israel to kiss and make up. Mainly for handling the Syrian situation. The Americans are training Syrian rebel fighters at camps in Jordan and Turkey (with UK assistance). The Americans are indirectly supplying arms by the CIA orchestrating the supply activities of the Arab gulf states. America also has special forces in position to act should the chemical weapons situation escalate. So have the Russians.
The problem is that all the American, UK and Gulf aid is wasted whilst Assad maintains air superiority. He can drop oil drums full of TNT from helicopters on to bread queues (a favourite tactic) with total impunity. So sooner or later, to some degree, that air superiority will need to be degraded. We won't give the rebels MANPADs because they could fall into the hands of salafists and end up being used at a civil airport near you. Though the rebels have captured some MANPADs and used them effectively. They shot down an Assad helicopter yesterday.
The safe zone makes a lot of sense because it can be very flexible and progressive and because the Patriot batteries are already in place. We could implement it this afternoon. Then gradually extend the size of it and implement SEAD. This would help stem the refugee tide, which has become a major problem. Also it would give the West a degree of political control, thus reducing the power of the salafists.
Politically we have learned a lot from Iraq, Afghanistan and Libya. With what we know now we would have done these campaigns very differently. We cannot get a country to switch instantly from being an oppressive dictatorship to being a Western liberal democracy. All we can do is to work towards the replacement regime being less bad. Mali being an example of how our doctrine has changed.
Some may say why should we. And they have a very valid point. The problems for the West iinclude young people being radicalised who then wage asymmetrical warfare against us, as in 9/11. Some would say that American policy has made this worse rather than better. Then there is our reliance on Arab petrochemicals. The situation here has changed very rapidly and very fundamentally with fracking in America. It has changed the global strategic balance. Then there are WMDs. Bliar and Bush lied to us about these so we are very cynical. However the Tokyo underground sarin attack proved just how devastating a small amount can be in the hands of the wrong people. And in Syria today there are lots of the wrong people and lots of nerve gas.
Syrian nerve gas:
NBC Weapons: What Is Known About Nerve Gas In Syria
"Syrian nerve gas is stored at some fifty locations all over the country." So we have an accident waiting to happen. The salafists could very easily release this in the London or New York undergrounds if they got their hands on it.