After Obama's intervention, will level playing fields in Syria become level killing fields?

Now that Barack Obama has decided to arm the ‘good’ rebels in Syria, it’s more likely than ever that Britain will follow suit. The G8 summit next week in Northern Ireland may well turn into a pre-war summit, which will certainly be interesting seeing as Putin will also be there. The Russians may respond by giving more arms to Assad and the level playing field may quickly turn into a level killing field. The Wall St Journal says that Obama has pretty much decided on a no-fly zone enforced by allied aircraft based in Jordan which will allow rebels to train. But which rebels? There are more than a dozen of them, some already fighting with each other. Can we be so sure that arms will not end up in the hands of the rebels who recently hoisted the black flag of al-Qaeda over a town they captured. And given that rebels have also used chemical weapons, what’s to stop Western air support being used to increase the cycle of violence, reprisals and civilian death?