In light of the massacre in Nairobi and yesterday’s conclusion of the appeals process for the Holsworthy Barracks plotters, it’s worth revisiting what threat al-Shabaab may pose within Australia.

Al-Shabaab came to public attention here in 2009 with Operation Neath, an investigation which resulted in five Melbourne men being charged with planning a mass shooting at Holsworthy army barracks in Sydney. Three of the men, all linked to al-Shabaab, were found guilty and sentenced to 18 years’ imprisonment.

The appeal decision this week again confirmed the danger this plot posed. The three convicted terrorists all tried to argue that the prosecution was a farce, one of them claimed he was set up by an undercover cop, and another claimed the judge was biased. Had their appeals succeeded it would have cast doubt on one of Australia’s largest terrorism investigations and damaged the legitimacy of Australia’s domestic counter-terrorism efforts.

Instead, the three appeal judges found their arguments baseless and upheld all of the convictions and sentences. They court also rejected the prosecution’s appeal attempt, who claimed that the sentences were not severe enough.

The planned Holsworthy attack demonstrated al-Shabaab posing a serious internal threat, though an indirect one, as the plot was an example of a self-starting terrorist cell emerging autonomously from what began as an al-Shabaab support network.

This was an al-Shabaab-linked plot, in that the cell members had raised money for al-Shabaab, sent people to train with them, and sought their endorsement for attacking Australian targets. However it was not an “al-Shabaab plot”, as the Somali jihadist organisation did not provide practical support or endorse the planned attack. They advised against the plot as it risked damaging their support base.

The terror attack in Nairobi potentially demonstrates that al-Shabaab has an increased willingness and capability to attack outside of Somalia, raising the possibility that its threat to Australia is higher now than it was when the Holsworthy plot occurred.

Is this the case? One cause for concern is that al-Shabaab’s relationship with al-Qaeda has changed. At the time of the Holsworthy plot, 2009, al-Shabaab was not a formal affiliate of al-Qaeda. However, in February 2012 al-Shabaab and al-Qaeda officially merged, meaning that “the constraints that previously held al Shabab back from sanctioning an attack, are in all likelihood removed.”

Therefore, if another group of Australian al-Shabaab supporters asked their permission for an attack, they would now be more likely to receive it.

However, my view is that there is less likely to be substantial connections between al-Shabaab and Australia today than there was prior to 2009, for four reasons.

First, al-Shabaab’s already limited popularity in the global Somali diaspora has declined in the past few years. Al-Shaabab is now less likely to be viewed as a nationalist resistance to the 2006 Ethiopian invasion and more as an extremist group, one that was partly responsible for the horror caused by the 2011 famine by attacking aid organisations.

Second, over the past year Shabaab’s emir, Ahmed Godane, has been killing many foreign jihadists in Somalia as part of an internal power struggle. This was the power struggle that resulted in the death of Omar Hammami, their most famous American member. Consequently, al-Shabaab is less welcoming to aspiring Western jihadists than it was when the Holsworthy plot occurred.

Third, the Commonwealth has proscribed al-Shabaab as a terrorist organisation in August 2009, making it easier to take legal action against its supporters.

Finally, Operation Neath resulted in the imprisonment of a key facilitator, Saney Aweys. This is significant because well-trusted intermediaries are very-often needed to connect aspiring jihadists with established jihadist organisations. Given the relatively small size of Australia’s jihadist scene, there aren’t usually many of these facilitators around at any one time, and curbing the activities of a small number of such individuals can have a large impact.

So, my take is that there are now less likely to be groups of Australian jihadists who are well-connected to al-Shabaab, and that we can therefore make an informed guess that al-Shabaab poses less of an internal threat today than it did in 2009.

The bad news is that if such groups do still exist and intend to carry out an attack, al-Shabaab, as a formal affiliate of al-Qaeda, is now more likely to support them.