The Islamic State group is getting smarter about circumventing Western security, and events like last month’s failed terror plot in Australia are likely to occur more frequently.

That’s the assessment of a former counterterrorism expert for Turkey’s national police following news reports last week that the Australian plot involved explosives and components that were shipped from Turkey.

Writing in the Wall Street Journal, Ahmet S. Yayla, an adjunct professor at George Mason University in Virginia, says the bomb materials used in the aborted attack likely arrived in Australia via air cargo – probably aboard a passenger jet -- evading all security measures.

Although the Australian operation ultimately failed, it was the type of plot that Western nations can expect to see more often, says Yayla, who from 2010 to 2013 led the counterterrorism and operations department of the Turkish National Police in Sanliurfa.

“Make no mistake,” Yayla writes. “Islamic State jihadists will continue trying to carry out spectacular terrorist attacks in the West.”

“Make no mistake. Islamic State jihadists will continue trying to carry out spectacular terrorist attacks in the West.” — Ahmet S. Yayla, Turkish counterterrorism expert

The reason: As ISIS fighters are driven out of places like Mosul, Iraq, and Raqqa, Syria, the terrorist group will be more likely to mobilize its sympathizers around the world, he says.

More precautions needed

As a precaution, governments across the West need to review the shipping and handling procedures for air cargo in their countries and enhance security measures to avoid plots similar to the one that occurred in Australia, Yayla urges.

He also suggests that NATO-member countries encourage Turkish authorities to crack down on jihadist cells operating in the country.

As Reuters has reported, two men – brothers Khaled Khayat and Mahmoud Khayat -- have been charged with conspiring to commit last month’s failed attack in Australia.

The reasons why the bombing plan was aborted aren’t entirely clear, but at a news conference Friday, Australian authorities said Khaled Khayat intended to have his brother unwittingly carry an explosive device aboard an airliner, but ultimately decided to end the mission.

The plan was “one of the most sophisticated plots that has ever been attempted on Australian soil,” Australian Federal Police Deputy Commissioner Michael Phelan said during the news conference, as Fox News reported.

The suspects based in Australia received the explosive materials from Turkey and went to the airport with the bomb in their luggage, authorities said, but abandoned the plot just before reaching airport security screening.

The suspects instead began working on a separate device that could release highly deadly hydrogen sulfide toxic gas, Yayla writes.

The Australian authorities found out about the terror plot almost two weeks later, following a tip from a foreign intelligence service, Yayla notes.

A senior diplomat in a position to know directly about the incident confirmed to Fox News the specifics of the plot and the authorities’ actions.

‘Lone Wolf’s Handbook’

Meanwhile, Yayla writes, ISIS supporters in Turkey last month published a 60-page “Lone Wolf’s Handbook,” a manual for teaching terrorists how to make a bomb or drive a truck into a crowd of pedestrians.

But it is not only so-called “lone wolves” who are a threat, Yayla writes. The Australian bomb plot was coordinated with an ISIS commander, possibly in Raqqa, who “coordinated” and guided the Khayat brothers for more than three months.

The commander had the bomb assembled with military-grade and high-end explosives, Yayla writes.