• The U.S. Treasury Department's Financial Crimes Enforcement Network issued an updated advisory to U.S. financial firms cautioning them on what to watch out for in illegal fentanyl trafficking, including the use of certain cryptocurrencies.

  • While FinCEN did cite four tokens -- bitcoin, ether, monero and tether -- the news of crypto's involvement in this illicit market has been well covered by previous criminal and sanctions actions from U.S. authorities.

Criminal organizations in Mexico have been using several popular digital assets to buy the raw materials needed to make the drug fentanyl, according to the U.S. Treasury Department's Financial Crimes Enforcement Network (FinCEN), which cited the use of bitcoin and other tokens in a Thursday advisory.

The cartels "are increasingly purchasing fentanyl precursor chemicals and manufacturing equipment" from China-based suppliers and paying in tokens including bitcoin {{BTC}}, ether {{ETH}}, monero {{XMR}}, and tether {{USDT}} "among others," according to an updated FinCEN advisory to alert U.S. financial firms about the network of criminal organizations producing the dangerous narcotic.

The payments often end up in the Chinese suppliers' hosted wallets at crypto firms, sometimes through a secondary money transmitter, according to the notice.

The new warnings, updating a FinCEN advisory from 2019, reflect problems that had already emerged in sanctions and criminal cases brought by U.S. authorities.

In October, the U.S. Department of Justice charged eight China-tied companies with illegal drug production, distribution and sales of precursor chemicals.

U.S. overdoses involving fentanyl have become the leading killer for those aged 18-45. The chemicals used to manufacture the dangerous drug often come from China and wind their way across multiple borders on their path to U.S. users of the synthetic opioid, which the Drug Enforcement Administration (DEA) says is 100 times more potent than morphine.

Read More: U.S. Sen. Elizabeth Warren Calls for Shutdown of Crypto Funding for Fentanyl