The largest counterterrorism operation in Australian history landed two individuals in court Thursday, foiling an alleged plot to publicly behead a civilian in Sydney, NBC News reports.
Authorities said they believed the Islamic State in Iraq and Syria (ISIS) was planning "violent" and "random acts" against the public in Australia.
"This is not just suspicion, this is intent, and that's why the police and security agencies decided to act," Prime Minister Tony Abbott told reporters.
One man was charged with conspiracy to commit acts in preparation of a terrorist act and financing terrorism, and the other man was charged with possessing ammunition without a license and unauthorized ownership of a prohibited weapon, according to New South Wales police.
More than 800 officers raided 25 properties across Sydney early Thursday morning after intelligence officials said they discovered that ISIS had planned an attack against the country. Nine of the individuals detained were released, according to a post on the police's Twitter account.
"The police activity today was about preventing this group at the earliest possible opportunity and ensuring their plans did not come to fruition," said Andrew Colvin, acting commissioner for the Australian Federal Police.
As the investigation continued Thursday, officials launched "Operation Hammerhead" to activate a statewide high-visibility police force in public places and transport hubs in Sydney. Officials also increased patrols at iconic locations and tourist destinations across the city.
Asked about the arrests overnight in Australia, U.S. Director of National Intelligence James Clapper told reporters the situation was "emblematic of the world we're in" and warned that ISIS terrorists are "very sophisticated recruiters and motivators."
The investigation came just hours after the U.S. House on Wednesday approved President Barack Obama's controversial proposal to arm and train moderate Syrian rebels in an effort to combat ISIS, a terrorist militia that has captured large swaths of territory throughout Iraq and Syria and recently beheaded two American journalists and a British aid worker.
The United States began launching airstrikes against ISIS in Iraq earlier this month to protect threatened religious minorities, and is now trying to build a coalition of countries to back its expanded efforts to destroy the terrorist group.