If I had to guess, (and I'm NOT an expert on this... it's just a guess...)
These bots are programmed to infiltrate "western" social media websites, online forums, BB services, etc with any of the following:
1) Data garbage and clutter to bog down and crash networks
2) Political unrest (I suspect this is a MAJOR problem among the big social media networks) **
3) Scamming users
** I suspect this is one of the reason for the rapid appetite for authoritarianism here in the west in addition to the overall social divisions plaguing our society today. There's no need for nukes and standing armies when armies of artificial intelligence "bots" are brainwashing us to hate and kill each other from within.