In 1971 US unilaterally scrapped the Bretton Woods and essentially stole the gold reserves. Other countries protested heavily but could not really do much.
US then transitioned to the petrodollar system where demand for and value of the dollar is/was ensured by dollar monopoly in oil trade. This was done with deals with oil producing countries with varying levels of coercion.
Granted it is in a country's best interest not to piss off the world's largest military. Silver or lead is a decision too.
When USA do the same, the non-USA dollar holders also take on the cost, same-same, excepting that is everyone around the World who trades in dollars. Which comes back to USA's military-industrial complex to some extent. It's like having the ability to steal a gram from every gold bar in the World.
They don't. If they aren't holding USD or something pegged to it then it is not devalued.