ISIS shipped high-grade military explosives from Turkey, and Islamic State leaders in Syria personally directed “one of the most sophisticated plots that has ever been attempted on Australian soil,” authorities said Friday, giving a unique window into an Islamist plot that nearly worked.

The ISIS plan would have used an unsuspecting Australian man boarding a flight at Sydney airport and carrying a bomb disguised as a meat mincer, Federal Police Deputy Commissioner Michael Phelan said at a news conference.

Two men – Khaled Khayat and Mahmoud Khayat – were charged late Thursday in the disrupted plan to blow up an Etihad Airways flight on July 15, Reuters reported.

Police said an ISIS commander in Syria gave the men instructions on how to build a “fully functioning IED,” sent explosives via air cargo from Turkey, and one of the men then gave the camouflaged bomb to his unsuspecting brother to take aboard a flight. But officials said the device never penetrated airport security or even got near the screening area.

“We'll be alleging that the person who was to carry the IED on the plane had no idea they were going to be carrying an IED,” Phelan said.

Though they were still gathering details, authorities believe one of the accused men left the airport and the unsuspecting brother boarded his plane. That man hasn’t returned to Australia yet.

The terrorists responsible for the plot also wanted to build a device that would release poisonous hydrogen sulfide gas in a public area, authorities said. Chemicals were allegedly recovered, but a device was not near completion.

Police initially arrested four men in the plot, one of whom has since been released and another who was being held without charge under counter-terror laws, Reuters reported.