Especially in Syria, which we must remember, is a synthetic multiethnic state created with the collapse of the Ottoman Empire and the end of League of Nations mandates, nobody knows who will take power if the Assad regime collapse. One thing is sure, in cases like Syria, whatever what is done, at the end, it won’t be pretty in any way.
2)The Guerrilla Syndrome: Military history had told us one thing, it is not a good idea for any smart country to be involved in a proxy war it is currently the case in Syria.
Why? Because in the Syrian case, except of the fact that they are against the Assad regime, the rebels have very few things in common. You also don’t know who you are fighting against and what are the technical capacities of the various rebels and mercenaries in this battlefield.
Also, it’s really a bad idea to arm rebels or give them financial support. As in the situation in the 1980’s had told us in places like Afghanistan, the US arming rebels (which were those fighting the Soviet Army) had made the situation bad to worse when they became the enemies to the US intervention in Afghanistan.
3)Collateral Damage: Even if an attack on Syria is only based on some strategic airstrikes, there is a strong chance that the Assad regime will try to pack civilian into so-called sensitive installations.
Civilians will then be used as bargaining chips, which will ironically make Assad regime stronger. Even with all the things the Assad regime had done, there is nothing like using the nationalist discourse (in this case against the US-based coalition bombing Syria) to add some credibility even to a failed regime like Assad regime in Syria in the last few years.
4)The cost of war. Many western countries are broke, so why go at war? I don’t know. It’s not only a question of public funds (war is indeed expensive) but also that it is crazy that military forces should risk their lives for playing the policeman of the world.
No wonder that many western politicians have learned absolutely nothing of the outcome of the mission in Afghanistan and Iraq or even Somalia where the foreign intervention in the early 1990’s did nothing to bring peace to this region of the world.
5)War as a political game. In the course of history, many politicians and other rulers had used the act of war as a sort of diversion or ploy to be more popular. Sometimes it worked really well but in other cases it backfired and failed miserably at the end.
Why should anyone be a prey in this ploy done by politicians who want to use war as a way to be more popular and in the same time to restrict our freedoms all in the name of security?
So in conclusion, as much as there is possibly a good case for humanitarian aid to help civilians and refugees affected by the war in Syria, military intervention in Syria is foolish, dangerous and a waste of time and resources.