Before the war on Iraq, I heard the argument that since we had been fairly friendly with Saddam while he was fighting Iran and murdering Iraqi Kurds, that we had no moral grounds for complaining about how terrible his regime was. Of course, that was twenty years ago, and an example of Cold War thinking on our part.
There is a common misperception that the Cold War wasn't a war-- but it was. Many lives were lost in the titanic struggle between "us" (the United Sates and the rest of the Free World) and "them" (the Soviet Union, China, and their puppets)-- a struggle for nothing less than the future of the world. The Soviets already ruled the various republics of the USSR with an iron fist, and had expanded their empire into Eastern Europe. The presence of US troops in Western Europe prevented the Soviets from making another land grab there after WWII, but the stage was set for confrontations elsewhere.
There was a catch, though, as explained by Steven Den Beste in an article which is mostly about North Korea:
After the Cuban Missile Crisis, both sides in the Cold War recognized that any time there was a direct head-to-head confrontation between the two sides there was too great a chance of ultimate catastrophe. So the majority of the hot battles in the Cold War were fought by proxies on at least one side, with one side perhaps being publicly and formally engaged and maybe even using its own troops, while the other side offered support to its proxy without being directly engaged. Both sides in the Cold war would smile and nod at one another and publicly pretend they weren't really quite having a war, sort of.
Of course, the use of proxy nations dated back at least to Korea. We were engaging Chinese troops directly, but at least it wasn't the Soviets, so that was "OK." We knew that there were Russian pilots flying in the Asian wars, but we looked the other way. As long as we weren't shooting at Soviets, as long as Soviets were shooting at Afghan rebels armed by us, and as long as their proxies-- several Arab nations-- were shooting at our proxy-- Israel-- then everything was "fine." The struggle could be carried out diplomatically and militarily at the same time. It was the way the game was played.
In Europe, the political situation was polarized on either side of the Iron Curtain. Naturally, the Soviets exported their authoritarian system to the Eastern Bloc countries, and we fostered democracy in the West. In the proxy nations to be used for fighting, though, neither side was incredibly picky. Most proxy nations were authoritarian, and therefore more like the Soviets, but few put up statues of Lenin. The flip side, of course, is that we didn't insist on statues of Thomas Jefferson. As long as a nation was vaguely stable, and somewhat interested in fighting designated enemies, then we could do business.
I recall the early radio reports of Iraq invading Kuwait back in 1990. It seems there was some confusion among Americans, who believed that Iraq was our friend, and Iran was our enemy (and the seemingly similar names didn't help, for most people). I heard from the radio, though, that Iraq was never really our friend-- just the enemy of the enemy. Simplistic, but descriptive.
Yes, the Cold War strategy was an unsavory means to an end. The question for the anti-war people is this: don't you want the US to rise above that era of Machiavellian manuvering? Allowing ourselves to be paralyzed by guilt would ensure that nothing useful is ever accomplished. Now that I think about it, though, complete paralysis isn't quite what the "anti-war" forces want. Many of those same people did want us to intervene in Liberia-- reasoning that since that country was set up by the US back in the 19th century, it's somehow our responsibility to fix the current situation.
So let's get this straight-- past involvement with Saddam's Iraq is supposed to rob us of any moral authority to set things right now, but much older involvement with Liberia necessitates US action. Nation-building in Iraq-- which is somewhat industrial, and possesses the world's most exportable natural resource-- is wrong... but theoretical nation-building in Liberia-- which has civil war-- was supposedly imperative. I'm sorry, folks-- while it is possible to export domestic unrest, the receiving country generally doesn't pay you for the favor. Iraq actually has something to build upon, and I cannot sufficiently stress the importance of that attribute when choosing which nations to build.