They must have heard how generous the US taxpayers are with foreign aid.
South Vietnam already learned that from the Vietnam War. My brother wrote home to tell me how often they'd find stuff that the Americans had sent in the hideouts of the Vietcong, and how much of it ended up on the black market....things as a G.I., he couldn't get from the Army.
Việt Nam doesn’t need the foreign aid and absolutely doesn’t want the Woke strings that come with it.