HO CHI MINH CITY, Vietnam  The Ha Tam jewelry shop here sells foreign currency the way a filling station sells gasoline. So it was only seconds after pulling in on his motorbike that Quan Phan had swapped a fistful of Vietnamese dong for a neat stack of $100 bills  United States $100 bills, to be precise.

“Vietnamese people always want to have dollars,” Mr. Phan, an engineer, explained before rejoining a rush-hour swarm of motorbike commuters. He said he routinely converted part of his salary into greenbacks.

Developing countries  and these days even developed ones like Greece and Spain  constantly strive to retain the confidence of fickle foreign investors. Vietnam has a slightly different problem. Its government is struggling to restore faith among domestic investors like Mr. Phan.

What Vietnamese fear is not that their government has developed an Athenian affinity for deficits and debt. Hanoi’s deficits are relatively modest, and it has not been in international financial markets long enough yet to rack up any serious i.o.u.’s. What makes them nervous is the suspicion that the governing Communist Party will do anything to hit its economic growth target before a party congress early next year, even if that means letting inflation get out of control.