Colombia’s health ministry recommended on Monday the immediate suspension of aerial spraying of a herbicide that kills coca plants. The move comes despite U.S.-financed efforts to clear out the cocaine crops, the Associated Press (AP) reported.

The decision comes as the World Health Organization classified glyphosate, which is sold as Roundup, as a carcinogen in humans last month. The Colombian ministry said it was acting in accordance with the constitutional court ruling, which states that it should take precautions in the light of a credible health risk. 

The country’s President Juan Manuel Santos has not yet responded to the ministry’s recommendation. Over the past 20 years, U.S. contractors have sprayed glyphosate in more than 1.6 million hectares (4 million acres) of land to kill the coca plants, whose leaves are used to make cocaine, the AP reported.

In August, the U.S. Customs and Border Protection officials seized 3,317 pounds of cocaine, worth over $37.6 million, and arrested four alleged drug smugglers, while patrolling the Caribbean Sea. Officials had reportedly found a suspicious vessel off the coast of Panama; three of the suspects were Colombian nationals. The drugs were reportedly likely headed to the United States.