The US Treasury Department announced on Wednesday that it has slapped sanctions on Mexican drug kingpin Raul Flores Hernandez and his network.

Apart from Hernandez and his Flores Drug Trafficking Organization, the US also put 21 Mexican nationals and 42 entities on the sanctions list as they were believed to be in relation to the Guadalajara-based drug trafficking cartel, said the treasury in a statement, Xinhua reported.

The action marks the largest single Kingpin Act action against a Mexican drug cartel network that the Treasury’s Office of Foreign Assets Control (OFAC) has designated.

The sanctions would freeze any assets that a blacklisted person or entity holds under US jurisdiction and ban any US individuals or companies from making business deals with them.

The designation was part of a larger collaborative effort between the US and Mexican government agencies.

“This major joint action reflects the US government’s close cooperation with our law enforcement partners in Mexico to stop the illegal flow of narcotics,” said OFAC Director John Smith in the statement.

Hernandez has operated for decades due to his longstanding relationships with other drug cartels and his use of financial front persons to mask his investments of illegal drug proceeds, Smith noted.