Sometimes the best action is no action at all. This couldn't be applied more appropriately to anyone other than the government.
While I agree that there are instances where bad things happen and it is out of everyone's control except for those involved, I largely dispute the idea that the government has to get involved every time something unfortunate happens in the world. In just about every instance where the government has gotten involved whether it be foreign affairs, domestic matters, drugs or policing the net result has almost always been counterproductive to the cause. Whether the driving forces be greed or fear I don't think it dismisses the fact they they are still wrong.
To address crime (not just addiction) or terrorism there needs to be a paradigm shift that has to occur. Passing more laws, increasing prison sizes or increasing military budget or going to war while might seem like a quick fix, doesn't really address the underlying problems and in most cases exacerbates them.
Law enforcement should really be handed over to the Healthcare Industry. Yes, healthcare, it's a very complicated problem whereas in most instances can be remedied by medication and/or therapy. There are qualified people who go to school for addressing things like this. Only the most heinous crimes where medical treatment has failed should additional measures be taken, not out of necessity for punishment but for public safety. Poverty and the media is another cause but I am not going to get into all the ways to address those as there are many.
As for military/war, going to war never solves anything. The bombings in Afghanistan and Iraq will do nothing but radicalize more people and give rise to additional attacks and hate groups. You mention Vietnam... there is nothing good that came out of the US involvement there. There are consequences to all the wars that have taken place and I can imagine that in the decades to follow you will begin to see the result of it, if not already. Any action taken with foreign nations needs to be handled a little more elegantly with a level of humanity, but most importantly not driven by profit, greed or fear.