The USA is not capable of intervening in the Middle East. The whole of US foreign policy in that region has been a shambles, right from the start.
In the 1980s Saddam Hussein was their friendly butcher who murdered enemies of the USA and kept the Kurds down, not forgetting the extent of the Kurdish nation, which if it ever did realise it's national rights would be the biggest oil rich nation in the world. Saddam went to war against Iran at the behest of the USA and waged a terrible 4 year war, which end in stalemate and the deaths of millions on both sides. Saddam's reward was supposed to be Kuwait, but as usual attitudes changed and after all no one likes a looser.
The goons at the pentagon under Bush Sr. launched a terrible war against Saddam, but having driven him out of Kuwait, did not have the strength or the will to put him down at that time. A second war under Bush Jr dislodged Saddam and created a failed state which lurched from one sectarian excess to another. Now Iraq has come fully under the influence of Iran who apparently dictates it's foreign policy. We have come full circle and the target of US foreign policy, Iran, is now the big boy on the block in the Middle East, an ally of Assad in Syria, of Iraq, of Hezbollah in Lebanon and the sworn enemy of Israel.
The fumbling, bumbling and bungling did not begin with Obama, it is simply the fullest expression of US foreign policy. They either get their arses kicked or make such a mess they make more enemies than friends.
The USA is now so weak militarily that it cannot intervene in the Middle East. If it tried to it would simply demonstrate that weakness and that would encourage the anti Israel coalition to settle a few old scores. Thanks to US intervention with the help of Britain, the Middle East is a powder keg which could explode over a single issue.
The regime in Syria has got the upper hand now and any help given to the opposition will simply prolong the agony. Far better to have a solution, even if it is not the desired one, because the people of Syria need peace above all else. Cannibalism and other atrocities are a clear sign of a demoralised army. I do not think the opposition can win.
In my personal view, the uprising in Syria was wrong to try and take on the regime militarily. Displays of solidarity with the soldiery coupled with mass strikes would have toppled the regime in time. The mass of opposition would have been hard to stop and in tens and twenties at first, then in greater numbers as time was passed, oppositionists among the army would have come over. In fact a major part of the armed uprising came from the army, but armed aggression instead of solidarity appeals, alienated the rest of the army, who, even though they may have disliked the regime, had no where else to go. This was a blunder of some magnitude and lessons for future uprisings have to be learned from it.
Sabre rattling by the likes of Britain and others, agreeing to send arms, will not make the rebels victorious, it will simply prolong the agony and cause Syria to further degenerate. It is clear that British foreign policy would see Syria in complete ruins rather than see Assad reassert his grip. They have forgotten nothing and learned nothing from the mess they helped create in Iraq and Afghanistan. They would arm Al-Queada just to see Assad lose power.
So against this impending catastrophe, the USA is for once in it's history doing the right thing in staying out of it. Obama is one of the weakest presidents the USA has had since Jimmy Carter. This is not due to any personal spinelessness, but stems from his position as the representative of the ruling elite of the USA. He has executive power but cannot use it. The republicans have savaged everything he has tried to do and he has let them get away with it. This tells us that there is little difference between Democrats and Republicans these days, there is a lot of name calling, on domestic policy, but it seems they are basically in agreement on foreign policy. OK they wheeled out McCain a few weeks back, but they know he is a spent force and convinces no one.
The USA is staying out of it, because it knows it can no longer intervene decisively and partial intervention could ignite the whole shooting match in the Middle East. This is not Obama policy but is a script written for him and approved by military men who stand in the shadows and oversee what goes on abroad. This is where the Republicans and Democrats see eye to eye and meet on equal terms, around the military conference tables.