The New York Times revealed more details last week about the activities of Islamic State’s external operations unit, the Amn al-Kharji. Central to the report was an extensive interview with returned German foreign fighter Harry Sarfo.

This isn’t the first time Sarfo has spoken to the media. Since his return from Syria in July 2015 and arrest by German authorities, he has given interviews to Der Spiegel and The Independent. And aside from including a (very worthwhile) video interview, little of what Sarfo said in the article was new.

What makes the story most noteworthy is that the events of the past few months are starting to make Sarfo’s testimony look worryingly accurate.

His claim that 'hundreds' of operatives have been actively sent back to Europe by Islamic State (rather than simply returning), seems less outlandish after a summer dominated by a series of terrorist attacks inspired or directed by Islamic State.

Sarfo’s claims are given further credence by unnamed US intelligence sources and other returnees. And Islamic State spokespeople (in contact with undercover journalists) have similarly referenced large numbers of trained and capable operatives in Europe.

I’d previously hoped that these figures were inflated. After all, consistency does not always equal accuracy. Terrorist groups seek to influence as well as inform those under their command.

But the more we learn about the importance of external operations within the Islamic State operational structure, the more feasible these figures appear. We know that several thousand individuals have left Europe for the Middle East since 2012. If the Amn al-Kharji was able to cherry-pick those best suited (and willing) to make the return journey, then this seems like a realistic ratio.

Indeed, the emerging links between Islamic State and the perpetrators of recent terrorist attacks in Germany suggest that the ‘lone wolf’ tag has been used far too quickly and widely. And that the wave of terrorist attacks in Europe has been largely (but not exclusively) directed by Islamic State.

The returning foreign fighter problem is not a new one for our intelligence agencies. What is new in the context of the NYT article is Sarfo’s explanation for how hundreds of individuals are apparently operating under the radar.

He refers to sleeper operatives based in Europe, responsible for ‘activating’ potential suicide attackers drawn in by Islamic State propaganda. And their use of ‘clean’, recent converts as intermediaries between the operatives and wannabe terrorists.

If this, and other parts of Sarfo’s testimony, sound like the plot of a spy movie, then perhaps we should not be surprised. Behind the on-screen jihadists are a number of former Baathists pulling the strings. Indeed, a key player in constructing the ISIS franchise in Syria (the now deceased Haji Bakr) was a former colonel in Saddam’s Air Defence Intelligence Service.

The success of Islamic State in Iraq and Syria has been built on a bureaucratic and complex governance structure, driven by individuals with experience in Saddam’s brutal military and intelligence apparatus. If Islamic State violence appears medieval, the strategy and tradecraft behind it is anything but

While Australia is not referenced by Sarfo, the sophistication of the modus operandi he outlines (and as demonstrated in Europe, the Middle East and beyond) remains a concern. With at least 40 Australians known to have returned from Iraq and Syria, the presence of ‘sleeper operatives’ cannot be ruled out.

Looking at South East Asia, references to Indonesian and Malaysian Islamic State recruits being sent back to establish networks are concerning but not surprising. There has been little evidence so far that networks in either country have benefited from the force-multiplying effect of returning foreign fighters. But the report is a reminder that the directed terrorist threat, while heightened in Europe, extends to our region.

Broadly speaking then, the NYT article provides yet more evidence of the priority given to external operations by Islamic State. And the complexity of the current counter-terrorism mission.

But it is important to recognise that the circumstances that allowed Islamic State to create a 'global portfolio of terrorists' no longer exist.

It is significantly harder for a foreign fighter to reach Syria and Iraq in 2016 than it was between 2012 and 2015. And the diminishing numbers that make it are arriving to a radically different and more challenging environment than that which allowed Islamic State to train and dispatch hundreds of individuals to Europe and beyond.

Identifying and disrupting the existing underground network will be a herculean task for intelligence agencies worldwide. But it is a finite task. As its Caliphate crumbles, Islamic State will be unable to replenish the network indefinitely.