The Mercenaries, also known as Smileys, were supporting antagonists in the 2018 film The First Purge.
When The First Purge project was failing to gain popularity, the organization that had put the project into action hired mercenaries to act as purgers. They wore masks and began murdering to make it seem that the “people“ were in favor of the Purge. Some of these mercenaries got really into character and dressed as police officers and klansmen to make it seem as if ordinary people were in agreement with the Purge.
These mercenaries appear to be trained soldiers. They are experts with firearms and melee combat. They carry sub-machine guns and assault rifles.