CANBERRA, Australia — Three men were arrested on Tuesday over an Islamic State group-inspired plot to attack a variety of Sydney targets including police and defense buildings, courts, churches and diplomatic missions, police said.

A 20-year-old suspect had been monitored by police for a year since he returned to Sydney from Lebanon, Australian Federal Police Assistant Commissioner Ian McCartney said. He was known to police in Lebanon.

The suspect is expected to be charged with preparing for a terrorist act and preparing to enter Afghanistan for the purpose of engaging in hostile activities on behalf of the Islamic State group, McCartney said, adding that he was to go to Afghanistan to take part in a separate plot. He could be sentenced to life in prison on each charge if found guilty.

“There were a number of plans both internationally in terms of him traveling overseas, but also a domestic plan which was evolving at the same time,” McCartney said.

A 23-year-old man is expected to be charged with being a member of a terrorist organization, the Islamic State group. He could be imprisoned for 10 years.

A 30-year-old man who is an associate of the other two was expected to be charged with obtaining financial benefit by deception through fraudulently claiming unemployment benefits. He too faces 10 years in prison. The men are expected to appear in a Sydney court by Wednesday.

McCartney said the planning was in its early stages, and that the men had yet to obtain guns or explosives.

The plot was the 16th major terrorist attack to be thwarted by police in Australia since the threat level was raised in September 2014, McCartney said.

Home Affairs Minister Peter Dutton said the case demonstrated Australia’s need for temporary exclusion orders like Britain has.

The government will introduce a bill to Parliament on Thursday that would allow him to prevent an Australian citizen from returning to Australia for a period of up to two years if that citizen posed a threat.

“This is incredibly important because it will be alleged in relation to one of the individuals who has been arrested and charged today that he returned from overseas as an Australian citizen and obviously given his activities that he’s alleged to have been involved in over the course of the last 12 months, has resulted in his arrest today,” Dutton told reporters.



“We obviously have a very serious threat in this country. The fact that now 16 attempted terrorist attacks have been disrupted successfully within our country says to the Australian public that this threat has not diminished, it’s not going away and it remains current, particularly when we got Australians overseas in a theater of war being trained by ISIL or being inspired otherwise on line and we want to deal with those people as best we can,” Dutton added. ISIL is an acronym for the Islamic State group.

Dutton said the three Sydney residents came to know each other by sharing extremist views online.

The Islamic State group is expanding its footprint in the mountains of northeastern Afghanistan, recruiting new fighters and plotting attacks on the United States and other Western countries, U.S. and Afghan security officials have told The Associated Press.

Nearly two decades after the U.S.-led invasion of Afghanistan, the extremist group is seen as an even greater threat than the Taliban because of its increasingly sophisticated military capabilities and its strategy of targeting civilians, both in Afghanistan and abroad. Concerns run so deep that many have come to see the Taliban, which have also clashed with IS, as a potential partner in containing it.

A U.S. intelligence official based in Afghanistan told the AP that a recent wave of attacks in the capital, Kabul, is “practice runs” for even bigger attacks in Europe and the United States.

Bruce Hoffman, director of the Center for Security Studies at Georgetown University, sees Afghanistan as a possible new base for IS now that it has been driven from Iraq and Syria.