Twitter said it had mistakenly suspended the accounts of open-source intelligence reporters posting about Russia’s military build-up around Ukraine, leading to many of them accusing the Russian state of launching a “bot” campaign against them.

Based on publicly available satellite imagery, open-source reporters have used social media to supply a steady commentary on the activities of Russian forces near the Ukrainian border, providing a valuable alternative source of information to western intelligence reports.

The people behind the suspended accounts said they believed they had been the target of an attack by Russian bots—computers that mimic the activity of human users—that had mass-reported their content as being suspicious. This led their content to be removed automatically by Twitter’s moderation technology.