It wasn’t hard to trace the origins, according to one target, HuffPo freelancer Talia Lavin. She noted that there were numerous 4chan threads where users bragged about using “sock puppet” accounts (that is, disposable) to conduct the campaign.

In a statement, Twitter said it was “disheartened” about the layoffs and was taking steps to prevent coordinated harassment “making the situation worse.” Some of the harassing tweets stayed up for hours, though, illustrating both the problems and challenges of implementing anti-hate and anti-harassment policies. It can be difficult to automatically block these campaigns, especially if they couch threats in harder-to-scan photos, but there are also limits to what the targets can do in response — it’s not realistic to make users file reports against every single harasser. It may be a long time before Twitter and others can swiftly crack down on these actions without creating unintended side-effects.