How widespread was the FEV research? [Forced Evolution Virus, the stuff in the vats in Fallout 1 that turn you into a super mutant and sterilize you. Maybe a centaur too, I'm not clear on where those came from, though they clearly are human based.] I thought they FEV work was all done in California?
If you accept F3 as canon, then it was also done in DC, if you accept Brotherhood of Steel (which was
awful and ignores a heap of established canon) then it was also done in Texas.
It would be kind of weird to have FEV pop up in non-US locations, since it was created and researched by West-Tek (and American defence contractor), but easy to justify. Given the global climate in the game though, it'd be pretty easy to add that a country (or three) had stolen FEV samples (perhaps even varying strains) as part of an espionage program - perhaps concerned with the idea of American Super Soldiers in Power Armour. If they had Mariposa strain, they could have worked to further develop it (the way the Enclave did to create Horrigan - all the advantages, none of the mental deficiencies that many share).
I think that FEV showing up in non-U.S. locations is about as odd as nuclear weapons research showing up in non-U.S. nations....
Espionage is the name of the game.... Well, Spycraft, anyway.

It will not be FEV - just a parallel development 'inspired by' (or the 'inspiration of') FEV.
The U.S. alone has at least three strains of FEV and the resulting Super Mutants. Given that many strains under development, I doubt that other nations would be far behind.
Though I was picturing FEV as being closer to the 'combat drugs' that were either developed or in development by all the major power blocs in WWII - the most famous is the Nazi-Cooker method of creating Crystal Meth.
Russia, in particular Stalin, continued work on combat drugs and 'super soldiers' - some of the early work on Steroids comes to mind.
If I remember properly, Switzerland already
has sufficient fallout shelters to enclose their entire urban population - or at least that was the case in the early eighties.
The Swiss Super Soldiers is more for my entertainment than anything else - though I really like them being trained as spies, not thugs. It gives them flexibility.
I think that to balance that I will give the Swiss Super Soldiers a shorter lifespan, or reliance on cybernetics - heart replacement, kidney augmentation, a less discriminating digestive tract. Now imagine what a Pulse grenade can do to them....
The Auld Grump