Opioid and fentanyl traffickers who worked on the dark web were put on notice following “Operation TorNado” by the Justice Department, the agency announced on Thursday regarding the international initiative.

The operation led to 354 arrests, 5.7 metric tons of drugs confiscated, along with 209 firearms and $234 million in cash and cryptocurrency.

The effort was done in collaboration with multiple federal government agencies, along with Europol. The mission took place in countries including the United Kingdom, Australia, New Zealand, Ireland, France and several others in addition to the U.S.

“Today we’re once again proving that the dark web is not beyond the reach of law enforcement,” Co-deputy FBI Director Christopher Raia said at a press conference, calling the “largest” initiative undertaken by the Joint Criminal Opioid and Darknet Enforcement group. The group, also known as JCODE, has the goal of tackling organizations that exacerbated the “fentanyl crisis,” according to Raia regarding the “coordinated enforcement.”

The FBI official said that because of the “magnitude” of the threat, partnership with different agencies and countries meant so much, calling it “absolutely essential.”

“Let today’s announcement to serve as a warning,” he said, saying that precise anonymity of the dark web is not truly a “shield” from consequences.