Three men were arrested on Tuesday over an ISIS-inspired plot to attack a variety of Sydney targets including police and defense facilities, 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. The suspect is expected to be charged with plotting a terrorist act and preparing to enter Afghanistan for the purpose of engaging in hostile activities on behalf of ISIS, 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 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. 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. The men were arrested in raids in the citys suburbs after their online activities raised suspicion. McCartney said the planning was in its early stages, but included moves to import weapons and explosives to target facilities in the central business district. New South Wales police assistant commissioner Mick Willing said the men "knew each other via social media" including WhatsApp and Telegram, and shared a "like-minded philosophy". 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.