Mexican smugglers used a pneumatic-powered cannon to propel cans packed with 85 pounds (38kg) of marijuana into the air and over a fence at the Mexican border near San Luis, Arizona, authorities said on Wednesday.
"We haven't seen this before," said Kyle Estes, a U.S. Border Patrol spokesman. "We've seen catapults, but nothing like this. That's for sure."
He estimated the marijuana's value at $42,500.
The plot was foiled when U.S. Border Patrol agents discovered the 33 pot-filled cans last week before they could be picked up by smugglers in an area about 500 feet from the border fence, on the United States side, Estes said.
Agents searching the area about 200 miles southwest of Phoenix recovered a carbon dioxide tank used to propel objects from the cannon, he said.
Smugglers have become increasingly inventive in trying to move contraband into the U.S. in light of stepped up efforts to crack down on border smuggling, Estes said.
U.S. authorities have added more fencing, agents and technologies including unmanned surveillance drones to tighten security along Arizona's border with Mexico in recent years.
Drug traffickers have responded with a variety of ruses including strapping marijuana loads to low-flying microlight aircraft and hurling it over the border fence using medieval-style catapults.
No one was arrested in connection with the latest scheme.
(Reporting By David Schwartz, Editing by Alex Dobuzinskis and Cynthia Osterman)