More like $2 T (combined Iraq-Afganistan $4.3T) https://www.warcosts.org/compare/iraq-vs-afghanistan-cost

So far.

Do you imply that it was really cheap, just like solar+batteries?

1 week national battery storage is totally doable. All we need to do is convince the rest of the planet to stop making GPUs, phones, computers, and EVs for the next decade, and then give us all their rocks. 78.4TWh is about $19T (all in costs) for a national battery grid for 1 week storage, could be built over ten years but would need the US to build and own double the current global output, not even considering where all the raw materials and labor comes from.