The snipers shot at the boat from a Lynx helicopter above waters between Venezuela and Puerto Rico to bring the smugglers to a halt.
The Ministry of Defence revealed that after storming the boat enforcement officers recovered about 350kg of cocaine, with another 650kg being thrown overboard by the crew before they were captured.
The snipers, from 43 Commando Fleet Protection Group, first fired warning shots on the traffickers to try and stop them.
But when their calls were ignored they took out the speedboat’s engines to stop it.
Captain Nigel Budd, commanding officer of Wave Knight - the Royal Fleet Auxillary ship which helped give chase - said the seizure showed the good work being done to stop drug smuggling from South America.
He said: ‘This high-speed intervention shows how the Royal Fleet Auxiliary and Royal Navy are making a difference around the world to tackle threats wherever they occur.
‘This seizure highlights how effectively the US Coast Guard, we and our allies are working together to disrupt and dismantle the criminal networks that depend on the flow of illicit drugs from South America into the United States, the Caribbean, and Europe.’
The speedboat was initially spotted by a maritime patrol aircraft, which then directed RFA Wave Knight to intercept.
It responded by launching its helicopter - which the MoD claim no boat can outrun.
The tanker, based in Portland in Dorset, is used as part of Operation Martillo, an international drugs-busting effort focused on the Carribean.
The speedboat’s crew and the drugs haul were later transferred to the US Coast Guard and handed over to authorities on Miami Beach.
RFA Wave Knight was launched in 2000 and began its service in 2003.
The ship is crewed by 72 Royal Fleet Auxillary personnel but can also take 26 members of the Royal Navy for helicopter and weapons systems operations.