Below the crust is the , which is a layer of hot rock, nearly 3000 km thick.

Its the mantle

Explanation:

It goes as follows

crust  thinkness 0-100 km

mantle 3000 km thick, solid made up of iron magnesium and silicon, dense hot and semi solid

outer core  liquid 5180 to 2880 km

inner core radius of 1220 km  located 6400 to 5180 km beneath the surface its dense make of iron and nickel. Hot 5400 degrees celcius 9800 degrees fahrenheit.

the only other powers were germany russia and uk and they were too busy fighting each other wearing each other down   that the us was becoming strong and they were becoming weaker