Now that the Islamic State caliphate across Syria and Iraq has been largely dismantled, the question among analysts remains as to what shape and form the group will take in 2018 and how it will manifest itself throughout the region.

Key points: The Islamic State has been set back very far in terms of its original ambitions

The Islamic State has been set back very far in terms of its original ambitions Trump's administration has so far not shown much coherence or consistency across the administration

Trump's administration has so far not shown much coherence or consistency across the administration There is now a geopolitical shift in the region in the wake of the Islamic State's territorial defeat

But rather than deeming the brutal militant group completely destroyed or defeated, counter-insurgency expert David Kilcullen explains that for now, it has just lost control of its cross-border Middle Eastern territory as it seeks to rebuild itself.

"It's fair to say that the territorial possessions of Islamic State — that is, all the cities they controlled and roughly one third of Iraq and Syria that they had at their height — that sort of territorial holding has been crushed," Mr Kilcullen told the ABC's The World program.

"What we've seen is that Islamic State has basically dropped back to guerrilla mode, it's biding its time, it's trying to build up.

"We've also seen this expansion of jihadist ideology and technique to a much wider network of people than existed before ISIS hit the scene."

Mr Kilcullen says while it was premature to say the problem is over, the militant group's loss of so much territory had been a significant development.

'Original ambitions set very far back'

Militant Islamist fighters take part in a military parade along the streets of Raqqa, Iraq, in June, 2014. ( Reuters )

"Islamic State was different from Al Qaeda primarily because it wanted to be a conventional state; it wanted to hold territory, have tanks and an army, administer populations and build a relatively conventional nation-state kind of structure in the Middle East," he said.

"By losing control of that, it's certainly been set back very far in terms of its original ambitions."

Mr Kilcullen says that the current situation being dealt with would be similar to what president Barack Obama faced up until mid-2014, when the Islamic State first broke out as a territorial force.

He described it as a kind of an "amorphous guerrilla group" that has been and will continue to be present in many different conflicts across the region.

And so with the defeat of Islamic State as a territorial entity, he said, another significant issue was the spawning of other groups, most notably a group called the Hayat Tahrir al-Sham — an Al Qaeda associate with whom it maintains a contentious relationship that runs Syria's north-western province of Idlib — that were becoming much more prominent as terrorist or jihadist groups in the region.

The 'fully-internationalised', complex conflict in Syria

Displaced Syrian children look out from their tents at Kelbit refugee camp, near the Syrian-Turkish border, in Idlib province, Syria. ( Reuters: Osman Orsal )

Although IS militants might have had their strongholds dismantled, the post-IS war still rages on across Syria — however, the target of the attacks from countries like Turkey has somewhat shifted.

"The other bigger issue is that we've now got a fully-internationalised, incredibly complex conflict in Syria that's drawing in Turkey or has already drawn in Turkey, Russia, various Kurdish groups, the Syrian regime itself, Arab Gulf States, Saudi Arabia, even Israel over the last few weeks," Mr Kilcullen said.

"And that's an extraordinarily messy conflict.

"It's not clear to me that either the Obama administration or the Trump administration had really thought beyond the defeat of ISIS to think about what do we want to happen after the caliphate, so-called, is crushed — and now we're dealing with the war after the war against ISIS without a really clear plan of what we want to see emerge.

"Or I should say there are people in the administration that have clear ideas, but it is not clear to be that the administration as a whole has an overall consistent point of view."

Trump administration's policy lacks consistency

President Donald Trump changes his mind — or his position — relatively frequently, Mr Kilcullen says. ( Reuters: James Lawler Duggan )

While the Trump administration's approach to the Islamic State issue had a "fairly high degree" of policy continuity with Obama's administration, said Mr Kilcullen, it so far has not been showing much coherence or consistency across the administration.

There were multiple different competing power centres pushing their own agendas, and some of them were incompatible, he said.

"For example, Rex Tillerson, who is the Secretary of State, has been pushing a particular line with respect to Korea and Russia and other issues, but he is reasonably often undermined by a tweet from the President.

"He is also contending with quite a different set of priorities being enunciated out of the US mission and the UN in New York under Nikki Haley.

"So you've got multiple different, competing power centres across the administration, and that's not just … in the realm of foreign policy, it seems to be a fairly common characteristic of the administration.

"Also of course, the President changes his mind — or changes his position — relatively frequently and that can tend to leave people on the wrong side of a policy line that changed overnight unexpectedly."

'Geopolitical shift': What now for the Kurds?

The Kurd's vote for independence last September "hugely offended and upset" the Turks. ( ABC News: Tracey Shelton )

Meanwhile, another point of contention through the war against IS has been that the Kurds — arguably the single most effective group in holding back the militant group from rapidly spreading throughout spare border towns — are now being targeted by surrounding countries.

Mr Kilcullen said the Americans — who backed and armed many Kurdish groups — were not abandoning the Kurds, as most analysts maintain, but that they are working with them in northern Syria, in a town called Manbij, near Afrin where Turkey recently had invaded.

He said the Kurd's vote for independence last September not only "freaked out" the Iraqi Government and their Iranian ally, but also "hugely offended and upset" the Turks.

"And the Turks are now taking a much harder line not only against Kurds in Turkey and Kurds in Syria, but against their former quite close partner in Iraqi Kurdistan," he said.

"So I think we're seeing a sort of a geopolitical shift in the region, where now that the immediate irritant of ISIS has gone away, people are being much more driven by geopolitics."

He said in geopolitical terms, the emergence of a fully autonomous or independent Kurdistan was "very disruptive" in what was already a complex and fraught region.

"And so I think that's what's driving a lot of the conflict that we're dealing with now," he said.

"It's sort of a return to geopolitics after the interlude of dealing with ISIS."