I was playing as the USSR, and Five-Year Plan was played against me. Defectors was the randomly selected card. It has a US event, so it triggers.
But, the event in question occurs when "played by USSR during Soviet action round". Does that event occur? It seems to me that it would trigger if I were the one who played Five-Year Plan, but since it was played on a US action round, nothing happens.
The card texts are:
USSR player must randomly discard one card. If the card has a US associated Event, the Event occurs immediately. If the card is a USSR associated Event or an Event applicable to both players, then the card must be discarded without triggering the Event.
Play in Headline Phase in order to cancel USSR Headline Event, including scoring card. Canceled card returns to Discard Pile.
If Defectors is played by the USSR during Soviet action round, the US gains 1 VP. (unless played on the Space Race)