Wang and Chen, both nationals of China, were expelled from Fiji on June 8, and then arrested by the Drug Enforcement Administration, the Justice Department said.

“The indictment unsealed today in the Southern District of New York is the next step in our fight against fentanyl,” U.S. Attorney Damian Williams for the Southern District of New York, said in a statement. “Today, we target the very beginning of the fentanyl supply chain: the Chinese manufacturers of the raw chemicals used to make fentanyl and its analogues.”

Amarvel Biotech allegedly advertised online its shipment of fentanyl precursor chemicals to the United States and to Mexico. It also guaranteed “stealth shipping” by using deceptive packaging, the Justice Department said.

Amarvel Biotech shipped more 200 kilograms of precursor chemicals from China to the United States during an undercover investigation by the DEA. A confidential source from the DEA texted Yang about the shipments of Fentanyl.

In March and June, Wang and Chen had several meetings with a confidential source from the DEA, during which they allegedly acknowledged the need to take additional security measures “because recently American government … seized some Mexican group and they followed the routes to China,” where the U.S. government found “our competitor in China.”

Attorney General Merrick Garland said that Friday’s arrests were part of an effort to crack down on those who supply drug cartels with items to make fentanyl.

“That includes not only going after the leaders of the Cartels, their drug and gun traffickers, their money launderers, security forces, and clandestine lab operators,” Garland said. “It also includes stopping the Chinese chemical companies that are supplying the cartels with the building blocks they need to manufacture deadly fentanyl.”

Earlier this month, the U.N. Office on Drugs and Crime released a report saying that Methamphetamine trafficking was accelerating in Asia.