Argument by incredulity
In Iraq, as with other conflicts, civilians bear the consequences of warfare. In the Vietnam war, 3 million civilians died; in the Democratic Republic of the Congo, conflict has been responsible for 3·8 million deaths; and an estimated 200 000 of a total population of 800 000 died in conflict in East Timor.33–35 Recent estimates are that
200 000 people have died in Darfur over the past 31 months.36 We estimate that almost 655 000 people—2·5% of the population in the study area—have died in Iraq. Although such death rates might be common in times of war, the combination of a long duration and tens of millions of people affected has made this the deadliest international conflict of the 21st century, and should be of grave concern to everyone.
You don't want to believe that George Bush might be responsible for "the deadliest international conflict of the 21st century" (so far), but there's nothing incredible about it.