USA and Australian authorities hacked into an app used by criminals to read millions of encrypted messages, leading to hundreds of arrests of suspected organised crime figures in 18 countries, Australian officials said on Tuesday.
It has led to drug trade arrests in Australia, Asia, South America and the Middle East.
The Australian Federal Police said that as a result of the operation, a total of 224 people were now facing more than 500 charges in Australia alone, while six underground drug labs were shut down and firearms and A$45 million (US$35 million) in cash was seized.
Australian Prime Minister Scott Morrison said the operation "struck a heavy blow against organised crime - not just in this country, but one that will echo around organised crime around the world". The phones could only send messages to another device that had the app and criminals needed to know another criminal to get a device.
New Zealand police said that after the Federal Bureau of Investigation had dismantled two other encryption services, it began operating its own encrypted device company called Anom.
More than 100 organised crime members have been arrested in Australia as part of the operation, initiated after the United States' FBI decrypted "Anom", an online communications platform used by gang figures.
Officers were able to read millions of messages in "real time" describing murder plots, mass drug import plans and other schemes.
"Essentially, they have handcuffed each other by endorsing and trusting AN0M and openly communicating on it - not knowing we were watching the entire time", AFP Commissioner Reece Kershaw said.
What did the authorities uncover?
Australian authorities said the sting was the nation's largest police operation and had involved 4,000 police officers.
In Australia, police were able to prevent mass shootings in suburbs and frustrate drug operations.
Dubbed "Operation Trojan Shield", forces in 16 countries monitored as members of the mafia, Asian crime syndicates and outlaw motorcycle gangs discussed drug deals, money laundering and even gangland hits.
"Knocking out their communications has been a key part of us disrupting the organised crime", Commissioner Kershaw said.
Executing Australia's largest number of search warrants in one day, police on Monday seized 104 firearms as well as nearly A$45 million ($34.9 million) in cash.
He said the app access had given law enforcement "an edge that it had never had before", but added the platform was just one of many messaging apps favoured by organised crime gangs. Roughly NZ$3.7m (£1.9m, $2.7m) of assets were seized.