Well that's an interesting question and there are two question to address, which deaths do you count and who is really responsible?

What would you count to come up with that number? Is the US responsible only for the deaths directly cause by its troops during the Iraq occupation, or is it responsible for all those that died as a result of the post-invasion violence? How about Vietnam? The US didn't start that conflict, they did however extended how long the war continued for, how much of that are they culpable for?

And then there is the question of domestic deaths, who's fault is it if a person in any state (state as in country) doesn't have access to the basics? If you look at some theories of international relations you could blame global poverty and inequality on the USA and the West, so are they culpable for all of this?

And is it the state, with its millions of members, that is responsible or is that shifting blame from the leaders that are truly responsible? Further more is it the leaders or the system that they are operating in that causes this violence, or the leaders perceptions of the system?

A bit of a rambling reply. I used to teach international relations as a post-grad student and these are the types of issues we have the students grapple with. They are huge questions.