It's a little more complicated than that. US inflation is actually good for emerging economies which borrow in dollars, because it eases their debt burden.
US inflation is even better for the US economy which borrow in todays dollars and repays in future diluted dollars which it earns in dollars.
Foreign entites tend to earn in foreign currency, although not always and which is why China for example recyles a lot of the US dollars they recieve back into US government bonds. However the whole thing opens foreign governments and entities up to the risk that the relative inflation rates will affect the currencies (which it does).
