I'd love to see how they could do that without being allowed to speculate on the currency and under rigid currency controls. Currency sovereignty means they can literally control who has the currency, speculators can't just buy it on the free market. A speculator would have to somehow acquire mass amounts of currency by trading physical goods or something else with real value for it (so no coming in with fistfulls of dollars and demanding they sell currency), and the government would be able to turn away customers that don't pass certain requirements.

Of course then the US declares them "currency manipulators" like it does to any country that asserts its currency sovereignty and hits them with sanctions, but it doesn't look like they're safe from the US as-is so I don't really see much of a difference.

This reeks of "the master protects his slaves and that's why slaves benefit from being enslaved"