Seems like the idea BETA might be manmade could prove true. It's a little early to be sure what that lab where they have BETA under proteïn control is. Is it just a lab where they study BETA and were able to control them enough for that, or is it really a lab where they create new/better BETA?

The infinites, that attack that spares US troops, how the USA are portrayed in that show and how it is the only place on earth that was never attacked might let us think BETA are in fact US weapons... It might even be they collaborated with the USSR to create them and the USSR used BETA against some of their "minor" federations they had trouble controling. Or it might be they sucked at controling BETA...

This is only anime, but hate for the USA and the Japanese Nationalism... just saying.