If you critically examine the source that provided you this number and follow the rabbit hole, you will probably learn that it is wildly pessimistic AND not telling you what you think it’s telling you. E.g. these estimates often include estimated casualties from sectarian violence that was merely uncorked by the Iraq war. You are clearly not taking pains to prevent the casual reader from assuming that 600k (already a specious number) were all directly killed at the hands of US soldiers.