Just tried to do bioterrorism 15-20 times and every single time it said "your scientists have accidently poisoned your own food supply"

I lost half my population and half my income in a matter of 20 turns and literally every single time it said I accidently poisoned my own country, 15-20 times in a row doesn't seem correct, it seems like something is wrong because almost every other spy attack has been successful up to this point

These are fun. Def they get trickier and trickier. I am not sure what the exact coding is, but given the power of this op I find running anymore than 3 a day can be risky. That would be a lot though 15 of them in a row. I have def seen a few backfiring but in general I never run more than 3-4 of these a day tops for the exact thing you mentioned (well, not 15 times in a row part... but yah wiping out half my own people with the op with just a few back fires).

There is also the possibility you were making more ops before a full 24 hours was up since your last ops. I have done this too. But that really does not explain 15 backfires, vs just simple fails.

Spy DR got you.

should just be a fail on DR not a backfire?

Bioterrorism stacks on a target. The odds of a backfire increase based on the number of stacks that the defending country has. You were likely spying a country that already had a large number of stacks.

Oh ya, I had already bioterrorism attacked him tons and tons of times in the previous days

It’s something close to 29 ops in 72 hours where you really notice spy dr in 1a and harmful stacking seems to work the same way. It gets worse as you go on.