For decades, Vietnam has bought nearly all of its arms from Russia/USSR. However, the changing geopolitical landscape applies a tension to this, and Vietnam must at least consider other options.

Resolves to the next country that Vietnam buys at least new 20 fighter jets from.

new= those specific aircraft not used by another country's military

Fighter jets: trainers won't count. So if for example Vietnam bought T-50s this wouldn't count, but FA-50s would.

I will add more options if anyone can make a compelling case; I think the current line up mostly accurately reflects the market. If the market goes on long enough more options will emerge.

For cases where the provenance of a plane is ambiguous, I am going from Wikipedia.