https://unusualplaces.org/the-underground-town-of-coober-pedy/

A standard three-bedroom cave home with living room, kitchen, and bathroom can be excavated out of the rock in the hillside for a similar price to building a house on the surface. However, dugouts remain at a constant temperature, while surface buildings need expensive air-conditioning.

Speaking to CNN‘s Fareed Zakaria on Friday, President Biden said he needed to send cluster bombs because Ukraine and the US are running out of ammunition. “This is a war relating to munitions. And they’re running out of that ammunition, and we’re low on it,” he said.

the FY2023 presidential budget request was $842 billion https://en.wikipedia.org/wiki/Military_budget_of_the_United_States

not enough for ammo, apparently.