The Bush's WMD charade surely was indirectly responsible for killing far more than 100k Iraqi civilians, perhaps more than a million. The infamous leaks showed us that the US gov and military were lying about the numbers, the actual number of Iraqis they directly killed was close to 109k back then (no minutes of silence for them on any September day).
http://abcnews.go.com/Politics/wikileaks-109000-deaths-iraq-...
Since you mentioned that, what is even less well-known is that Bill Clinton's administration "saved" 500k Iraqi infants from the Saddam regime between 1991 and 1996 by sanctions that refused everything including life-saving drugs into Iraq. What's reported even less frequently is that Secy of State Madeline Albright thought about it: http://www.fair.org/index.php?page=1084/ Lesley Stahl on U.S. sanctions against Iraq: We have heard that a half million children have died. I mean, that's more children than died in Hiroshima. And, you know, is the price worth it?
Secretary of State Madeleine Albright: I think this is a very hard choice, but the price--we think the price is worth it.
--60 Minutes (5/12/96)
Remember who was in Iraq shaking hands with Saddam and delivering killing machines in 1980s? https://www.google.com/search?q=saddam+rumsfeld
I'm not blaming fellow Americans for it, we're too busy watching celebrity gossip, who cares whether our tax money goes to kill thousands of protesters via dictators or to kill millions of civilians through our own machines.