The Royal Canadian Mounted Police (RCMP) said it arrested four men who used a low-flying helicopter to avoid detection of the illegal transport of cannabis from Canada into the U.S.

Law enforcement officials seized the Jet Ranger helicopter used by the men, following a 16-month investigation conducted jointly with U.S. Homeland Security Investigations into the illegal import of guns and cannabis, the RCMP said on Wednesday.

The law enforcement partners executed six search warrants and seized over 800 plants and dried cannabis and around 400 grams of cocaine, as well as illegal handguns in an operation conducted with the assistance of the Ontario Provincial Police, the RCMP said. The searches were conducted in the Greater Toronto area and Quebec, the RCMP said.

While Canada legalized cannabis for recreational use in 2018, marijuana is illegal in the U.S. under federal law, although several U.S. states allow its use. It is illegal to leave Canada with cannabis, and its growth in Canada is regulated.

The four men, all residents of Ontario, were charged with violations of the Criminal Code of Canada including conspiracy to commit the unlawful export of cannabis, possession of cannabis for the purpose of exporting it and cultivating cannabis not at a dwelling house, the RCMP said.