You:

The European colonial project that built the US killed literally hundreds of millions of people in the US alone

Your source places the highest estimates for a north American population at seven million. Most likely it was half that. "Hundreds of millions of people in the US alone" is what I am contesting.

Them's fighting words

We brought pigs into existence for the benefit of human conditions, we will take them out of it if and when it becomes necessary.

So called ethical treatment impacts the speed and scope of research that can be done, and in doing so delays or prevents the benefits of conducting that research. That means that people who could be saved by animal tested medicines instead die in the time taken to find an alternative.

This source supports me as far as I can tell.

What's gross is condemning people to die for the sake of some pigs

I would see a million pigs die before one human.

Hydro destroys environments, uses enormous amounts of concrete and the related disasters have killed orders of magnitude more people than nuclear.

This is the future those damn communists want! They're going to force their hideous art deco infrastructure and nerfarious drug-filled public transport on us!

The entire population of North and South America at the start of that project did not exceed a hundred million, and the vast majority of it was in central and southern America. There were not hundreds of millions of people in the US to kill.

Very possibly, every native American living within the modern borders of the US from 1400 to today might have totalled a hundred million, but the colonial project didn't kill literally every one of them.

Iraq and Afghanistan had their militaries levelled in a matter of days. It's the occupation that created problems

It's neither of those things. Words have meanings, and legal terms have very specific meanings.