Background: Throughout the Cold War there were people crossing sides, in both directions, whether dissidents, exposed spies, or those attracted by the ideology of the other superpower.

Effect: 2 OPs recurring USA event. If played as a headline event cancels USSR headline. If played for Ops by USSR, USA gains 1 Vp.

Numbering Noteespite being an Early War event, this is card nunmber 103, last on the list. Not sure why that is.

Strategy: This a powerful little card, since the Headline+first action combo is one of the big Soviet strengths. As well as directly preventing the combo by cancelling the headline, the fear of Defectors can mean the USSR plays relatively weak events as headlines rather than going for the strongest combination available. As USSR this is a good card to keep in your hand until just after a reshuffle, so that you can make your headlines in peace.

what would happen if USSR played it as an headline? surely he would have better choices... but would he lose 1 VP or what?

No, because you can't play it for Ops (thus not triggering the 1 vp part). It would just cancel your own headline event. It would be a bad play.

If the USSR played Defectors as a headline nothing would happen: the card would cancel the USSR headline, which is Defectors...

While not the strongest of USSR headlines, there are circumstances where you might choose to play it. For example, if USA can see your headline (via Space Race) then it isn't safe to play a Scoring Card, so if your hand was just Scoring cards and USA events Defectors might be the least among the various evils.

What happen if USSR player play a US Event as a headline value ? ( a nasty one)

If I read well, the US event is not triggered !

it can be a good way to get rid of a really unpleasant event

Yes, Defectors can cancel a US event played as headline by Soviets. If the Soviets can see the US headline in advance (using the Space Race ability) and they see Defectors they can do this safely. If they can't see the US headline then its a bit risky.

Same thing for Scoring cards which would be bad for the USSR, you can try to get them cancelled by Defectors too.

yes, that is exactly what has just happened in my game.

He(US) played Defectors , so I discarded Grain Sales that I was holding for 3 turns. I am too far on Space race to Space race Grain Sales ...

good opportunity !