U.S. border officials in California seized a record-breaking shipment of meth, about 1.7 tons (3,400 pounds) worth around $1.3 billion, hidden in speakers and headed Down Under.

Authorities say that the haul of meth broke two records, winning the dubious honor of being the largest amount of meth to be seized on U.S. soil as well as the largest amount ever to be shipped to Australia. Some cocaine and heroin were also found hidden inside the speakers.

The seizure was a joint effort between U.S. Homeland Security, the DEA and the Australian Federal Police (AFP). On January 11, they managed to discover the drugs hidden inside of a huge shipment of speakers which were packed away in dozens of metal boxes.

Authorities have arrested two U.S. citizens and four Australian citizens in connection with the shipment, believing them to be part of a larger U.S.-based drug syndicate shipping drugs worldwide.

The Australian authorities involved say that the bust prevented “a tsunami of ice” from reaching their country, which would have manifested as an estimated 17 million hits of meth. This would have been an especially large problem for the Australian state of Victoria, where the meth was headed, as sewage drug monitoring has found that the 6.3 million people living there use about 2 tons of meth per year.

AFP Assistant Commissioner Bruce Hill claims that these drugs originate from Mexican cartels that have been pushing hard to get their products into Australia.

“They have been sending smaller amounts over the years. This is now flagging intent Australia is now being targeted,” Hill told reporters. “The cartel is among one of the most powerful and violent drug trafficking syndicates in the world.”

The previous largest seized meth shipment ever headed to Australia was a 1.3-ton shipment caught in December of 2017.