That there must be a form of global law enforcement is a natural result of changes in the world, over which we have no control. Each of us is destined to choose what form that governance may take.
Here, now, we have an emerging force in the world that can act to cut back the growth of socialism and brutality. That may seem a little "imperialistic", but in the absence of such action, the UN's paradigm will predominate, and the planet will continue the flush itself down a rathole.
People yearning for liberty everywhere will follow a strong lead, and support the overthrow of evil in their own countries; but someone has to lead : that leadership has devolved upon the US, UK, Austrailia, Poland, and others.
There is a race between communism allied with brutality and the Jeffersonian idiology of limited government subordinate to the natural liberties of persons. The UN espouses the former; the Anglosphere, the latter. By choosing to allow dictators to have what they will in their own countries, you also tacitly endorse tyranny: tyranny can not survive without parisitically feeding on prosperous, free nations. They are, by nature, propelled to swollow up societies like the one in which you live.
And as if that knowledge would not be enough to have one choose a position on the side of aggressive support of liberty, I would think that the simple knowledge that somewhere--anywhere--there was a human subject to brutality by the likes of Saddam, would be enough to move the heart and mind toward resolute counter-offense. We owe that support by virtue of our humanity, in addition to our interest in self-preservation.
I recall a network TV news story about one 19 year-old boy in Afghanistan who taught himself English and studied history by means of an illegal satellite dish and forbidden books. He hid the Oxford English Dictionary under the floorboards in his bedroom. For him, alone, was the liberation of that place worth the effort: he was at risk of death for his pursuits. I said to myself, " Here is a future leader of Afghanistan!"
As to attacking tyranny and brutality everywhere at once: that's impossible; but Iraq is a good place to start.
You have a choice: support action against all those evil bastards, or isolate yourself from "foreign entanglements" until the armies they nurture beat down your door.
Here, here. We must discern the moral course as a guide to our activities. While we cannot effectively free every people on Earth from tyranny at this time, we can recognize the objective and let it illuminate our course as we go forward.