The facts are simple, really:
1. After the fiasco in Egypt - how Mubarak was prosecuted and possibly going to get his head chopped off - no Arab leader will risk stepping down peacefully. They will fight to the last bullet, unless offered pardon in the West with all their stolen property (NOT going to happen, being that everyone wants to by chummy with the powers to be). Gaddafi, Asad the the Yemenite leadership are an example of this.
This has happened, in a large part, as a result of Obama throwing Mubarak to the dogs. No one trusts US word anymore.
2. No one has the right to militarily intervene in domestic conflicts like that. If they want, let them have their own revolution. Give them arms, talk to them, give them money, but don't move one soldier near their country. Reason is, you'll end up being blamed for propping this in the first place and be an excuse for even greater oppression ("It's an American-Zionist scam, I tell you!").
3. Furthermore, the demographics of these countries are pretty complex with tribes and factions that have opposed interests. Whom will you go with? It'll turn to a bloody civil war no matter what.
4. As a side note, the only reason Egypt is peaceful now is that... Nothing really happened. The same guys just took over from Mubarak, they are all military elites. Basically it was a peaceful revolution sponsored by Western idiocy. Gave up Mubarak to get few generals and a much vaguer policy on Iran and Hamas. And I stand alone, watching the idiot liberals cheering the "Arab Spring" and laughing to myself. If only they knew things aren't that simple in the Arab world; You don't change hundreds of years of ignorance, oppression and zealot theology for democracy overnight, fools.
5. Israel has no interest seeing Asad leaving post in Syria. I'm sure Israel asked very nicely that no one takes any action. It will only tie more military resources that should really be spent on Iran, and might ignite another conflict on its northern borders. "Better the devil you know" is the key paradigm here; throw Asad out and you won't know what you'll get, but you can sure as hell bet on Iranian meddling that might bring up an even worse regime.
6. Meanwhile Asad is sending Syrians to the Israeli border to heat up things and take the world's eyes off his oppression but no one is buying that (
outside of the UN of course).
As the protesters become aggressive, so do the rulers. This will not end soon and will not end in Syria. Let them win it for themselves. We have still yet to see even one positive thing out of this ridiculous "Arab Spring". Unnecessary bloodshed to replace one violent faction with another, that's all it is.