...levels of "murder" are there in the US code.

Murder 1 and 2

Manslaughter

Involuntary Manslaugher.

And what is generally the basis for differentiation.

Intent.

Your opponent insists on continually adding >to kill children< to the language. He is adding intent to his logical alternatives to frame the argument in such a way as you cannot win

Because there is no logical difference between flying a plane into a building >to kill children< and launching a missile into a building >to kill children<.

There is a world of difference between flying a plane onto a building with the express purpose of killing thousands of innocent civilians and launching a missile at a military target.

In the end...both may result in people dying.

But is it capital murder?

Or is it involuntary manslaughter?

Or is it self-defense?

Thats the argument he can't win. So thats the argument he won't make.