The United States sanctioned nine members of Mexico’s Sinaloa Cartel and the leader of Colombia’s Clan del Golfo drug trafficking group on Tuesday, according to the US sanctions office OFAC.

Colombian native Jobanis de Jesus Avila Villadiego, also known as Chiquito Malo, is thought to be the current leader of Clan del Golfo, which the US State Department claims is responsible for the majority of cocaine manufacturing and trafficking in Colombia.

Avila Villadiego is accused of orchestrating a murder campaign against Colombian security agents last year in response to the revelation that a former Clan del Golfo commander would be deported to the US.

OFAC also sanctioned nine Mexico-based individuals it said were responsible for drug trafficking on behalf of the Sinaloa Cartel and its Los Chapitos wing.

These include alleged fentanyl traffickers Liborio Nunez Aguirre, Samuel Leon Alvarado and Carlos Mario Limon Vazquez, accused of operating a network of laboratories that synthesize precursor chemicals into fentanyl for distribution in the United States.

Brothers Leobardo and Martin Garcia Corrales were also accused of using proceeds from fentanyl sales to buy automatic rifles, grenades and other weapons, according to OFAC.

The U.S. office also sanctioned Jorge Humberto Figueroa Benitez, whom it accused of commanding a violent group of Los Chapitos sicarios, and Mario Alberto Jimenez Castro, accused of operating a money laundering organization using virtual currency and wire transfers.

It also sanctioned two alleged associates of Jimenez Castro; Julio Cesar Dominguez Hernandez whom it accused of importing and selling cocaine and methamphetamine in the United States, and Jesus Miguel Vibanco Garcia, accused of importing fentanyl.

The United States has been seeking increased cooperation from both Mexico and China in curbing the flow of fentanyl and its precursor chemicals, which have fueled a sharp rise in U.S. overdose deaths.