It's ironic that the Coast Guard's derogatory nickname is "puddle pirates" since it's one of the few agencies in the U.S. that actually gets called on to fight modern pirates.
Anti-piracy, along with anti-narcotics missions, are often handled by the Coast Guard's Law Enforcement Detachments, or LEDETS, and Tactical Law Enforcement Teams, or TACLETs.
These Guardians are deployed on Coast Guard cutters as well as U.S. or allied Navy ships. From there, they are sent to board and search vessels where the crew are suspected of committing a crime, generally piracy or the smuggling or drugs, humans, or money.
Here's how the Coast Guard catches the bad guys on the high seas:
1. Once Navy or Coast Guard intelligence has identified and approached a suspect vessel, LEDET or TACLETs move in.